MySQL PREPARE Statements PREPARE, EXECUTE and DEALLOCATE PREPARE Statements
Example
PREPARE prepares a statement for execution
EXECUTE executes a prepared statement
DEALLOCATE PREPARE releases a prepared statement
SET @s = 'SELECT SQRT(POW(?,2) + POW(?,2)) AS hypotenuse';
PREPARE stmt2 FROM @s;
SET @a = 6;
SET @b = 8;
EXECUTE stmt2 USING @a, @b;
Result:
+------------+
| hypotenuse |
+------------+
| 10 |
+------------+
Finally,
DEALLOCATE PREPARE stmt2;
Notes:
- You must use @variables, not DECLAREd variables for
FROM @s - A primary use for Prepare, etc, is to 'construct' a query for situations where binding will not work, such as inserting the table name.
