# Functions in TiDB

+ Functions accept input data or no data
+ The return value of a function can be part of an expression
+ General syntax:
  + **`{function_name}([arg1 [, arg2, ..., argn]])`**  
    + Separate multiple parameters with commas
+ Statement **`SHOW BUILTINS`** to list all built-in functions
+ Examples:
  + **`NOW()`**: Returns the current date and time
  + **`TIDB_VERSION()`**: Returns the `TiDB` server version

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In SQL statements, expressions can be used in places such as the ORDER BY or HAVING clause of a SELECT statement, the WHERE clause of a SELECT/DELETE/UPDATE statement, or a SET statement. Expressions can be written using literal values, column names, NULL, built-in function, operators, etc.