# `EXECUTE` 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`.