# Execution Phase
+ If the statement contains any question mark placeholder, you must provide a user variable with a compatible data type value for each placeholder, as shown below
  + `EXECUTE ... USING ...` 
```
SET @var1 = 'Simon'; 
EXECUTE prepared_stmt ~!@USING@!~ @var1;
SET @var2 = 'Teddy';
EXECUTE prepared_stmt ~!@USING@!~ @var2;
```

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The USING clause must name as many values as there are parameter markers in the statement, and values are substituted in the same order they are listed.

If you refer to a user variable in a prepared statement that has not been set, its value is NULL.