DO
DO
executes the expressions but does not return any results. In most cases, DO
is equivalent to SELECT expr, ...
that does not return a result.
In MySQL, a common use case is to execute stored procedure or trigger. Since TiDB does not provide stored procedure or trigger, this function has a limited use.
Synopsis
- DoStmt
- ExpressionList
- Expression
DoStmt ::= 'DO' ExpressionList
ExpressionList ::=
Expression ( ',' Expression )*
Expression ::=
( singleAtIdentifier assignmentEq | 'NOT' | Expression ( logOr | 'XOR' | logAnd ) ) Expression
| 'MATCH' '(' ColumnNameList ')' 'AGAINST' '(' BitExpr FulltextSearchModifierOpt ')'
| PredicateExpr ( IsOrNotOp 'NULL' | CompareOp ( ( singleAtIdentifier assignmentEq )? PredicateExpr | AnyOrAll SubSelect ) )* ( IsOrNotOp ( trueKwd | falseKwd | 'UNKNOWN' ) )?
Examples
This SELECT statement pauses, but also produces a result set.
mysql> SELECT SLEEP(5);
+----------+
| SLEEP(5) |
+----------+
| 0 |
+----------+
1 row in set (5.00 sec)
DO, on the other hand, pauses without producing a result set.
mysql> DO SLEEP(5);
Query OK, 0 rows affected (5.00 sec)
mysql> DO SLEEP(1), SLEEP(1.5);
Query OK, 0 rows affected (2.50 sec)
MySQL compatibility
This statement is understood to be fully compatible with MySQL. Any compatibility differences should be reported via an issue on GitHub.