Assign an SQL result to variable from prepared statement in MySQL?

For this, use stored procedure. Let us first create a table −

mysql> create table DemoTable(Id int, Name varchar(100));
Query OK, 0 rows affected (1.51 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable values(10,'John');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable values(11,'Chris');
Query OK, 1 row affected (0.41 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+------+-------+
| Id | Name    |
+------+-------+
| 10 | John    |
| 11 | Chris   |
+------+-------+
2 rows in set (0.00 sec)

Following is the query to assign SQL result to variable from prepared statement in MySQL −

mysql> DELIMITER //
mysql> CREATE PROCEDURE Prepared_Statement_Demo( nameOfTable VARCHAR(20), IN nameOfColumn VARCHAR(20), IN idColumnName INT)
BEGIN
   SET @holdResult=CONCAT('SELECT ', nameOfColumn, ' INTO @value FROM ', nameOfTable, ' WHERE id = ', idColumnName);
      PREPARE st FROM @holdResult;
      EXECUTE st;
      DEALLOCATE PREPARE st;
   END //
Query OK, 0 rows affected (0.20 sec)
mysql> DELIMITER ;

Call the stored procedure using call command −

mysql> call Prepared_Statement_Demo('DemoTable','Name',10);
Query OK, 0 rows affected, 2 warnings (0.00 sec)

Now check the value of variable @value −

mysql> select @value;

This will produce the following output −

+--------+
| @value |
+--------+
| John   |
+--------+
1 row in set (0.00 sec)