|SQL*Plus User's Guide and Reference
An authorized user of an operating system or a product (such as Oracle database server or Oracle Forms). Depending on the operating system, may be referred to as ID, User ID, login, and so on. Accounts are often created and controlled by a system administrator.
In SQL, a temporary name assigned to a table, view, column, or value within a SQL statement, used to refer to that item later in the same statement or in associated SQL*Plus commands.
The way in which data is positioned in a field. It may be positioned to the left, right, center, flush/left, flush/right, or flush/center of the defined width of a field.
A PL/SQL program unit that has no name and does not require the explicit presence of the BEGIN and END keywords to enclose the executable statements.
Recovery structure where online redo log files are archived before being reused.
Redo log mode where the filled online redo log files are archived before they are reused in the cycle. In ARCHIVELOG mode, the database can be completely recovered from both instance and disk failure. The database can also be backed up while it is open and available for use. However, additional administrative operations are required to maintain the archived redo log. See also archived redo log.
A data item following the command file name in a START command. The argument supplies a value for a parameter in the command file.
Processing performed on multiple rows of data rather than one row at a time. In some Oracle utilities such as SQL*Plus, Export/Import, and the precompilers, users can set the size of the array; increasing the array size often improves performance.
A convention for using digital data to represent printable characters. ASCII is an acronym for American Standard Code for Information Interchange.
A feature unique to SQL*Plus that enables SQL*Plus to automatically commit changes to the database after every successful execution of a SQL command or PL/SQL block. Setting the AUTOCOMMIT variable of the SET command to ON enables this feature. Setting the AUTOCOMMIT variable to n enables this feature after every n successful INSERT, UPDATE or DELETE commands or PL/SQL blocks.
A non-interactive process that runs in an operating system environment and performs some service or action. Certain Oracle database server products use background processes for different tasks, such as performing and coordinating tasks on behalf of concurrent users of the database, processing and delivering electronic messages, and managing printing services.
A reference to a parameter used to replace a single literal value (for example, a character string, number, or date) appearing anywhere in a PL/SQL construct or a SQL SELECT statement. For a bind reference, you must precede the parameter name with a colon (:).
A variable in a SQL statement that must be replaced with a valid value, or the address of a value, in order for the statement to successfully execute.
The smallest unit of data. A bit only has two possible values, 0 or 1. Bits can be combined into groups of eight called bytes; each byte represents a single character of data. See also byte.
In PL/SQL, a group of SQL and PL/SQL commands related to each other through procedural logic.
A report region that contains the bulk of the report (text, graphics, data, and computations).
An event, such as a change in the value of an expression, that occurs while SQL*Plus processes a query or report. You can direct SQL*Plus to perform various operations, such as printing subtotals, whenever specified breaks occur.
A column in a report that causes a break when its value changes and for which the user has defined break operations.
A group containing one or more break columns.
The order in which SQL*Plus checks for the occurrence of breaks and triggers the corresponding break operations.
Indicates the order in which to display a break column's data. Valid options are Ascending and Descending.
A report that divides rows of a table into "sets", based on a common value in the break column.
An area where the user's SQL statements or PL/SQL blocks are temporarily stored. The SQL buffer is the default buffer. You can edit or execute commands from multiple buffers; however, SQL*Plus does not require the use of multiple buffers.
A group of eight sequential bits that represents a letter, number, or symbol (that is, a character). Treated as a unit of data by a computer.
An Oracle datatype provided for ANSI/ISO compatibility. A CHAR column is a fixed-length column and can contain any printable characters, such as A, 3, &, or blanks, and can have from 1 to 2000 characters or can be null.
A single location on a computer system capable of holding one alphabetic character or numeric digit. One or more characters are held in a field. One or more fields make up a record, and one or more records may be held in a file or database table.
A group of sequential letters, numerals, or symbols, usually comprising a word or name, or portion thereof.
A part of a SQL statement that does not constitute the full statement; for example, a "WHERE clause".
A user, software application, or computer that requests the services, data, or processing of another application or computer (the "server"). In a two-task environment, the client is the user process. In a network environment, the client is the local user process and the server may be local or remote.
A standard Oracle datatype. The CLOB datatype is used to store single-byte character large object data, and can store up to 4 gigabytes of character data.
A vertical space in a database table that represents a particular domain of data. A column has a column name and a specific datatype. For example, in a table of employee information, all of the employees' dates of hire would constitute one column. A record group column represents a database column.
An expression in a SELECT statement that defines which database column(s) are retrieved. It may be a column name or a valid SQL expression referencing a column name.
A heading created for each column appearing in a report.
An instruction to or request of a program, application, operating system, or other software, to perform a particular task. Commands may be single words or may require additional phrases, variously called arguments, options, parameters, and qualifiers. Unlike statements, commands execute as soon as you enter them. ACCEPT, CLEAR, and COPY are examples of commands in SQL*Plus.
A file containing a sequence of commands that you can otherwise enter interactively. The file is saved for convenience and re-execution. Command files are often called by operating-system specific names. In SQL*Plus, you can execute the command file with the START, @ or @@ commands.
A line on a computer display on which typed in commands appear. An example of a command line is the area next to the DOS prompt on a personal computer. See also prompt.
The text, by default SQL>, with which SQL*Plus requests your next command.
A language construct for the inclusion of explanatory text in a program, the execution of which remains unaffected.
To make permanent changes to data (inserts, updates, deletes) in the database. Before changes are committed, both the old and new data exist so that changes can be stored or the data can be restored to its prior state.
Used to perform runtime calculations on data fetched from the database. These calculations are a superset of the kinds of calculations that can be done directly with a SELECT statement. See also formula column.
In Net8, the set of instructions for preparing network communications, as outlined in the Net8 documentation.
Files that are used to identify and characterize the components of a network. Configuration is largely a process of naming network components and identifying relationships among those components.
To identify yourself to Oracle by entering your username and password in order to gain access to the database. In SQL*Plus, the CONNECT command allows you to log off Oracle and then log back on with a specified username.
The set of parameters, including a protocol, that Net8 uses to connect to a specific Oracle instance on the network.
In an editor, such as the SQL*Plus editor, the line in the current buffer that editing commands will currently affect.
A set of operating system files, treated as a unit, in which an Oracle database server stores a set of data dictionary tables and user tables. A database requires three types of files: database files, redo log files, and control files.
(1) A person responsible for the operation and maintenance of an Oracle database server or a database application. The database administrator monitors its use in order to customize it to meet the needs of the local community of users. (2) An Oracle username that has been given DBA privileges and can perform database administration functions. Usually the two meanings coincide. There may be more than one DBA per site.
Failure that occurs when a problem arises that prevents an Oracle database instance (SGA and background processes) from continuing to work. Instance failure may result from a hardware problem such as power outage, or a software problem, such as operating system crash. When an instance failure occurs, the data in the buffers of the SGA is not written to the datafiles.
An object stored in the local database that identifies a remote database, a communication path to the remote database, and optionally, a username and password for it. Once defined, a database link can be used to perform queries on tables in the remote database. Also called DBlink. In SQL*Plus, you can reference a database link in a DESCRIBE or COPY command.
Something created and stored in a database. Tables, views, synonyms, indexes, sequences, clusters, and columns are all examples of database objects.
The node or computer at which the ORACLE Server kernel runs. The database server holds the database, runs the ORACLE Server kernel, is not a MS-DOS PC or Macintosh (but could be an OS/2 PC), and runs a multitask operating system.
An alphanumeric code that identifies a database, used to specify the database in Net8 operations and to define a database link. In SQL*Plus, you can reference a database specification in a COPY, CONNECT, or SQLPLUS command.
A string of Net8 parameters used to indicate the network prefix, the host system you want to connect to, and the system ID of the database on the host system.
The category of SQL statements that control access to the data and to the database. Examples are the GRANT and REVOKE statements. Occasionally DCL statements are grouped with DML statements.
The category of SQL statements that define or delete database objects such as tables or views. Examples are the CREATE, ALTER, and DROP statements.
A comprehensive set of tables and views automatically created and updated by the Oracle database server, which contains administrative information about users, data storage, and privileges. It is installed when Oracle is initially installed and is a central source of information for the Oracle database server itself and for all users of Oracle. The tables are automatically maintained by Oracle. It is sometimes referred to as the catalog.
The category of SQL statements that query and update the database data. Common DML statements are SELECT, INSERT, UPDATE, and DELETE. Occasionally DCL statements are grouped with DML statements.
The mechanisms that control the access and use of the database at the object level. For example, data security includes access to a specific schema object and the specific types of actions allowed for each user on the object (for example, user SCOTT can issue SELECT and INSERT statements but not DELETE statements using the EMP table). It also includes the actions, if any, that are audited for each schema object.
(1) A standard form of data. The Oracle datatypes are CHAR, NCHAR, VARCHAR2, NVARCHAR2, DATE, NUMBER, LONG, CLOB, NCLOB, RAW, and LONG RAW; however, the Oracle database server recognizes and converts other standard datatypes. (2) A named set of fixed attributes that can be associated with an item as a property. Data typing provides a way to define the behavior of data.
A standard Oracle datatype used to store date and time data. Standard date format is DD-MMM-YY, as in 23-NOV-98. A DATE column may contain a date and time between January 1, 4712 BC to December 31, 4712 AD.
A clause or option value that SQL*Plus uses if you do not specify an alternative.
See local database.
On some operating systems, a named storage space for a group of files. It is actually one file that lists a set of files on a particular device.
A database that is not mounted by any instance, and thus cannot be opened and is not currently available for use.
The number of characters or spaces allowed to display the values for an output field.
A standard Oracle database table named DUAL, which contains exactly one row. The DUAL table is useful for applications that require a small "dummy" table (the data is irrelevant) to guarantee a known result, such as "true."
A program that creates or modifies files.
The person for whom a system is being developed; for example, an airline reservations clerk is an end user of an airline reservations system. See also SQL*Plus.
A message from a computer program (for example, SQL*Plus) informing you of a potential problem preventing program or command execution.
A formula, such as SALARY + COMMISSION, used to calculate a new value from existing values. An expression can be made up of column names, functions, operators, and constants. Formulas are found in commands or SQL statements.
On some operating systems, the second part of the full file specification. Several standard file extensions are used to indicate the type or purpose of the file, as in file extensions of SQL, LOG, LIS, EXE, BAT, and DIR. Called file type on some operating systems.
A collection of data treated as a unit, such as a list, document, index, note, set of procedures, and so on. Generally used to refer to data stored on magnetic tapes or disks. See also filename, extension, and file type.
On some operating systems, the part of the filename that usually denotes the use or purpose of the file. See extension.
Columns contain information in one of four types; users can specify how they want a query to format information it retrieves from character, number, date, or long columns. For example, they can choose to have information of type date appear as 23/11/98, or Monday Twenty-third November 1998, or any other valid date format.
A clause element that controls the appearance of a value in a report column. You specify predefined format models in the COLUMN, TTITLE, and BTITLE commands' FORMAT clauses. You can also use format models for DATE columns in SQL date conversion functions, such as TO_DATE.
A control character that, when executed, causes the printer to skip to the top of a new sheet of paper (top of form). When SQL*Plus displays a form feed on most terminals, the form feed clears the screen.
Manually-created column that gets its data from a PL/SQL procedure, function, or expression, user exit, SQL statement, or any combination of these.
A PL/SQL subprogram that executes an operation and returns a value at the completion of the operation. A function can be either built-in or user-named. Contrast with procedure.
In SQL*Plus, text that names an output column, appearing above the column. See also column heading.
The computer from which you run SQL*Plus.
The background processes and memory area required to access an Oracle database. A database system requires one instance and one database. An Oracle database server consists of an SGA and a set of Oracle database server system processes.
Recovery of an instance in the event of software or hardware failure, so that the database is again available to users. If the instance terminates abnormally, then the instance recovery automatically occurs at the next instance startup.
An algorithm for expressing a date in integer form, using the SQL function JDATE. Julian dates allow additional arithmetic functions to be performed on dates.
Defines the label to be printed for the computed value in the COMPUTE command. The maximum length of a COMPUTE label is 500 characters.
See Log Writer (LGWR).
The database that SQL*Plus connects to when you start SQL*Plus, ordinarily a database on your host computer. Also called a default database. See also remote database.
To perform a sequence of actions at a terminal that establishes a user's communication with the operating system and sets up default characteristics for the user's terminal session.
To terminate interactive communication with the operating system, and end a terminal session.
A background process used by an Oracle instance. LGWR writes redo log entries to disk. Redo log data is generated in the redo log buffer of the system global area. As transactions commit and the log buffer fills, LGWR writes redo log entries into an online redo log file.
A user-specified command line, used to run an application that is connected to either a local or remote database. The logon string either explicitly includes a connect string or implicitly uses a default connect string.
One of the standard Oracle datatypes. A LONG column can contain any printable characters such as A, 3, &, or a blank, and can have any length from 0 to 2 gigabytes.
A database associated with an Oracle instance. The database may be opened or closed. A database must be both mounted an opened to be accessed by users. A database that has been mounted but not opened can be accessed by DBAs for some maintenance purposes.
Allows many user processes to share a small number of server processes, minimizing the number of server processes and maximizing the utilization of available system resources.
A standard Oracle datatype. The NCHAR datatype specifies a fixed-width national character set character string, and can have a maximum column size up to 2000 bytes.
A standard Oracle datatype. The NCLOB datatype is used to store fixed-width national character set character (NCHAR) data, and can store up to 4 gigabytes of character text data.
Oracle's remote data access software that enables both client-server and server-server communications across any network. Net8 supports distributed processing and distributed database capability. Net8 runs over and interconnects many communications protocols. Net8 is backward compatible with SQL*Net version 2.
A group of two or more computers linked together through hardware and software to allow the sharing of data and/or peripherals.
A value that means, "a value is not applicable" or "the value is unknown". Nulls are not equal to any specific value, even to each other. Comparisons with nulls are always false.
The absence of a value.
A standard Oracle datatype. A NUMBER column can contain a number, with or without a decimal point and a sign, and can have from 1 to 105 decimal digits (only 38 digits are significant).
A standard Oracle datatype. The NVARCHAR2 datatype specifies a variable-length NCHAR string. NVARCHAR2 width specifications refer to the number of characters if the national character set is fixed-width, and to the number of bytes if the national character set is varying-width. The maximum column size allowed is 4000 bytes.
An object is an instance of an object type. In Oracle8, objects can be persistent (i.e. stored in the database) or transient (i.e. PL/SQL or Oracle Call InterfaceTM (OCI) variables). See also object type.
A database model that combines the key aspects of the relational and object data models into a single system. Oracle8 is an object-relational database system.
A user-defined type that models a structure and behavior of an object. Equivalent to the concept of a class in different programming languages. In Oracle8, object types have public interfaces with attributes and methods. Object types are also known as abstract data types.
(1) Redo log files that have not been archived, but are either available to the instance for recording database activity or are filled and waiting to be archived or reused. (2) A set of two or more online redo log files that record all committed changes made to the database.
A database that has been mounted and opened by an instance and is available for access by users. If a database is open, users can access the information it contains. See also mounted database.
The system software that manages a computer's resources, performing basic tasks such as allocating memory and allowing computer components to communicate.
A non-procedural tool for creating, maintaining, and running full-screen, interactive applications (called "forms") in order to see and change data in an Oracle database. A fourth-generation language for creating interactive screens for use in block-mode, character-mode or bit mapped environments. It has a define time and a runtime component.
The relational database management system (RDBMS) developed by Oracle Corporation. Components of the RDBMS include the kernel and various utilities for use by database administrators and database users.
The relational database management system (RDBMS) sold by Oracle Corporation. Components of Oracle Server include the kernel and various utilities for use by DBAs and database users.
Results of a report after it is run. Output can be displayed on a screen, stored in a file, or printed on paper.
File to which the computer transfers data.
A method of encapsulating and storing related procedures, functions, and other package constructs together as a unit in the database. While packages provide the database administrator or application developer organizational benefits, they also offer increased functionality and database performance.
A screen of displayed data or a sheet of printed data in a report.
Some hardware architectures (for example, loosely coupled processors) allow multiple computers to share access to data, software, or peripheral devices. With systems that have the parallel server option, Oracle can take advantage of such hardware platforms by running multiple database instances that share a single physical database. In appropriate applications, the Oracle Parallel Server allows access to a single database by the users on multiple machines with increased database performance.
A substitution variable consisting of an ampersand followed by a numeral (&1, &2, and so on.). You use parameters in a command file and pass values into them through the arguments of the START command.
A secondary identification word (or string of alphanumeric characters) associated with a username. A password is used for data security and known only to its owner. Passwords are entered in conjunction with an operating system login ID, Oracle username, or account name in order to connect to an operating system or software application (such as the Oracle database). Whereas the username or ID is public, the secret password ensures that only the owner of the username can use that name, or access that data.
The Oracle procedural language extension of SQL. PL/SQL combines the ease and flexibility of SQL with the procedural functionality of a structured programming language, such as IF...THEN, WHILE, and LOOP. Even when PL/SQL is not stored in the database, applications can send blocks of PL/SQL to the database rather than individual SQL statements, thereby reducing network traffic.
A set of SQL and PL/SQL statements grouped together as an executable unit to perform a very specific task. Procedures and functions are nearly identical; the only difference between the two is that functions always return a single value to the caller, while procedures do not return a value to the caller.
(1) A thread of control in an operating system; that is, a mechanism in an operating system that can execute a series of steps. Some operating systems use the terms job or task. A process normally has its own private memory area in which it runs.
(1) A message from a computer program that instructs you to enter data or take some other action. (2) Word(s) used by the system as a cue to assist a user's response. Such messages generally ask the user to respond by typing some information in the adjacent field. See also command line.
A SQL SELECT statement that retrieves data, in any combination, expression, or order. Queries are read-only operations; they do not change any data, they only retrieve data. Queries are often considered to be DML statements.
The data retrieved by a query.
A standard Oracle datatype, a RAW data column may contain data in any form, including binary. You can use RAW columns for storing binary (non-character) data.
An Oracle7 (and earlier) term. Refers to the software used to create and maintain the system, as well as the actual data stored in the database. See also Relational Database Management System (RDBMS), Server, Oracle Server and Oracle RDBMS.
A synonym for row; one row of data in a database table, having values for one or more columns.
A sequential log of all changes made to the data. The redo log is written and used in the event of a failure that prevents changes from being written to disk. The redo log consists of two or more redo log files.
A file containing records of all changes made to the database. These files are used for recovery purposes. See also redo log.
An Oracle7 (and earlier) term. A computer program designed to store and retrieve shared data. In a relational system, data is stored in tables consisting of one or more rows, each containing the same set of columns. Oracle is a relational database management system. Other types of database systems are called hierarchical or network database systems.
In SQL*Plus, a comment you can insert into a command file with the REMARK command.
A computer on a network other than the local computer.
A database other than your default database, which may reside on a remote computer; in particular, one that you reference in the CONNECT, COPY, and SQLPLUS commands.
(1) The results of a query. (2) Any output, but especially output that has been formatted for quick reading, in particular, output from SQL*Plus.
(1) A word that has a special meaning in a particular software or operating system. (2) In SQL, a set of words reserved for use in SQL statements; you cannot use a reserved word as the name of a database object.
Named groups of related privileges that are granted to users or other roles.
To discard pending changes made to the data in the current transaction using the SQL ROLLBACK command. You can roll back a portion of a transaction by identifying a savepoint.
(1) Synonym for record; one row of data in a database table, having values for one or more columns. Also called tuple. (2) One set of field values in the output of a query. See also column.
A collection of logical structures of data, or schema objects. A schema is owned by a database user and has the same name as that user.
The combination of a hierarchical classification and a set of non-hierarchical compartments that represent the sensitivity of information.
To fetch rows from one or more database tables using a query (the SQL statement SELECT).
The list of items that follow the keyword SELECT in a query. These items may include column names, SQL functions, constants, pseudo-columns, calculations on columns, and aliases. The number of columns in the result of the query will match the number of items in the SELECT list.
A SQL statement that specifies which rows and columns to fetch from one or more tables or views. See also SQL statement.
Oracle software that handles the functions required for concurrent, shared data access to an Oracle database. The server portion receives and processes SQL and PL/SQL statements originating from client applications. The computer that manages the server portion must be optimized for its duties.
The time after a username connects to an Oracle database and before disconnecting, and the events that happen in that time.
See system variable.
See also System Global Area (SGA).
Sending or saving output to a disk storage area. Often used in order to print or transfer files. The SQL*Plus SPOOL command controls spooling.
The internationally accepted standard for relational systems, covering not only query but also data definition, manipulation, security and some aspects of referential integrity. See also Data Manipulation Language (DML), Data Definition Language (DDL), and Data Control Language (DCL).
The default buffer containing your most recently entered SQL command or PL/SQL block. SQL*Plus commands are not stored in the SQL buffer.
See SQL statement.
A file containing SQL statements that you can run in SQL*Plus to perform database administration quickly and easily.
A complete command or statement written in the SQL language. Synonymous with statement (SQL).
An Oracle tool used to load data from operating system files into Oracle database tables.
Net8's precursor. An Oracle product that works with the Oracle Server and enables two or more computers that run the Oracle RDBMS or Oracle tools such as SQL*Forms to exchange data through a network. SQL*Net supports distributed processing and distributed database capability. SQL*Net runs over and interconnects many communications protocols.
An interactive SQL-based language for data manipulation, data definition and the definition of access rights for an Oracle database. Often used as an end-user reporting tool.
A SQL statement, and analogous to a complete sentence, as opposed to a phrase. Portions of SQL statements or commands are called expressions, predicates, or clauses. See also SQL statement.
Any sequence of words or characters on a line.
In SQL*Plus, a variable name or numeral preceded by one or two ampersands (&). Substitution variables are used in a command file to represent values to be provided when the command file is run.
In a report, a total of values in a number column, taken over a group of rows that have the same value in a break field. See also summary.
Summaries, or summary columns, are used to compute subtotals, grand totals, running totals, and other summarizations of the data in a report.
A line in a report containing totals, averages, maximums, or other computed values. You create summary lines through the BREAK and COMPUTE commands.
The orderly system by which commands, qualifiers, and parameters are combined to form valid command strings.
See also SYSTEM username.
Privilege that contains all system privileges with the ADMIN OPTION and the SYSOPER system privilege. See also SYSOPER.
Privilege that allows a DBA to perform operations such as STARTUP, SHUTDOWN, ARCHIVE LOG and RECOVER. See also SYSDBA.
A person responsible for operation and maintenance of the operating system of a computer.
The text editor provided by the operating system.
A shared storage area that contains information required by user processes and background processes, such as data and control information for one Oracle instance.
The SGA is allocated when an Oracle instance is started, and is deallocated when the instance shuts down.
One of two standard DBA usernames automatically created with each database (the other is SYS). The Oracle user SYSTEM is created with the password MANAGER. The SYSTEM username is the preferred username for DBAs to use when performing database maintenance.
A variable that indicates status or environment, which is given a default value by Oracle or SQL*Plus. Examples are LINESIZE and PAGESIZE. Use the SQL*Plus commands SHOW and SET to see and alter system variables.
The basic unit of storage in a relational database management system. A table represents entities and relationships, and consists of one or more units of information (rows), each of which contains the same kinds of values (columns). Each column is given a column name, a datatype (such as CHAR, NCHAR, VARCHAR2, NVARCHAR2, DATE, or NUMBER), and a width (the width may be predetermined by the datatype, as in DATE). Once a table is created, valid rows of data can be inserted into it. Table information can then be queried, deleted, or updated. To enforce defined business rules on a table's data, integrity constraints and triggers can also be defined for a table.
A temporary substitute name for a table, defined in a query and only good during that query. If used, an alias is set in the FROM clause of a SELECT statement and may appear in the SELECT list. See also alias.
A program run under your host computer's operating system that you use to create and edit host system files and SQL*Plus command files containing SQL commands, SQL*Plus commands, and/or PL/SQL blocks.
An internal storage area created by the TIMING command.
One or more lines that appears at the top or bottom of each report page. You establish and format titles through the TTITLE and BTITLE commands.
A logical unit of work that comprises one or more SQL statements executed by a single user. According to the ANSI/ISO SQL standard, with which Oracle is compatible, a transaction begins with the user's first executable SQL statement. A transaction ends when it is explicitly committed or rolled back by the user.
To discard or lose one or more characters from the beginning or end of a value, whether intentionally or unintentionally.
A column contains information in one of four types: character, date, number or long. The operations users can perform on the contents of a column depend on the type of information it contains. See also format.
A command line argument that allows you to specify your Oracle username and password with an optional Net8 address.
The name by which a user is known to the Oracle database server and to other users. Every username is associated with a private password, and both must be entered to connect to an Oracle database. See also account.
A variable defined and set by you explicitly with the DEFINE command or implicitly with an argument to the START command.
An Oracle Corporation datatype. Specifically, this datatype functions identically to the Oracle VARCHAR2 datatype (see definition below). However, Oracle Corporation recommends that you use VARCHAR2 instead of VARCHAR because Oracle Corporation may change the functionality of VARCHAR in the future.
An Oracle Corporation datatype. Specifically, it is a variable-length, alpha-numeric string with a maximum length of 4000 characters. If data entered for a column of type VARCHAR2 is less than 4000 no spaces will be padded; the data is stored with a length as entered. If data entered is more than 4000, an error occurs.
A named object that holds a single value. SQL*Plus uses bind substitution, system, and user variables.
The width of a column, parameter, or layout object. Width is measured in characters; a space is a character.
A reporting or output feature in which a portion of text is moved to a new line when the entire text does not fit on one line.