Returns character data, with all letters lowercase. The character data can be of the data types CHAR and VARCHAR2. The return value is the same data type as the character data. The database sets the case of the characters based on the binary mapping defined for the underlying character set.


See the syntax of the LOWER function in Oracle Database SQL Language Reference.


The following restrictions apply when you use the TOLOWER function in the SELECT command:

  • The function does not support LOB data types, including BLOB, CLOB, NCLOB, and BFILE data types.

  • The function does not support national character set data types, including NCHAR, NVARCHAR2, and NCLOB data types.


This example shows each problem_key in all lowercase letters.

select tolower(problem_key) from problem;