MySQL Tutorial/Procedure Function/Dynamic Statement

Create a dynamic statement in a procedure

mysql>
mysql> CREATE TABLE Employee(
    ->     id            int,
    ->     first_name    VARCHAR(15),
    ->     last_name     VARCHAR(15),
    ->     start_date    DATE,
    ->     end_date      DATE,
    ->     salary        FLOAT(8,2),
    ->     city          VARCHAR(10),
    ->     description   VARCHAR(15)
    -> );
Query OK, 0 rows affected (0.08 sec)
mysql>
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->              values (1,"Jason",    "Martin",  "19960725",  "20060725", 1234.56, "Toronto",  "Programmer");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(2,"Alison",   "Mathews",  "19760321", "19860221", 6661.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(3,"James",    "Smith",    "19781212", "19900315", 6544.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(4,"Celia",    "Rice",     "19821024", "19990421", 2344.78, "Vancouver","Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(5,"Robert",   "Black",    "19840115", "19980808", 2334.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(6,"Linda",    "Green",    "19870730", "19960104", 4322.78,"New York",  "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(7,"David",    "Larry",    "19901231", "19980212", 7897.78,"New York",  "Manager");
Query OK, 1 row affected (0.01 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(8,"James",    "Cat",     "19960917",  "20020415", 1232.78,"Vancouver", "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> select * from Employee;
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| id   | first_name | last_name | start_date | end_date   | salary  | city      | description |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
|    1 | Jason      | Martin    | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto   | Programmer  |
|    2 | Alison     | Mathews   | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester      |
|    3 | James      | Smith     | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester      |
|    4 | Celia      | Rice      | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager     |
|    5 | Robert     | Black     | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester      |
|    6 | Linda      | Green     | 1987-07-30 | 1996-01-04 | 4322.78 | New York  | Tester      |
|    7 | David      | Larry     | 1990-12-31 | 1998-02-12 | 7897.78 | New York  | Manager     |
|    8 | James      | Cat       | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester      |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE set_col_value
    ->        (in_table     VARCHAR(128),
    ->         in_column    VARCHAR(128),
    ->         in_new_value VARCHAR(1000),
    ->         in_where     VARCHAR(4000))
    ->
    -> BEGIN
    ->    DECLARE l_sql VARCHAR(4000);
    ->    SET l_sql=CONCAT_ws(" ",
    ->                "UPDATE",in_table,
    ->                   "SET",in_column,"=",in_new_value,
    ->                " WHERE",in_where);
    ->    SET @sql=l_sql;
    ->    PREPARE s1 FROM @sql;
    ->    EXECUTE s1;
    ->    DEALLOCATE PREPARE s1;
    -> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql> call set_col_value("Employee","id","999","id=1");
Query OK, 0 rows affected (0.00 sec)
mysql> drop procedure set_col_value;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> select * from EMployee;
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| id   | first_name | last_name | start_date | end_date   | salary  | city      | description |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
|  999 | Jason      | Martin    | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto   | Programmer  |
|    2 | Alison     | Mathews   | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester      |
|    3 | James      | Smith     | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester      |
|    4 | Celia      | Rice      | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager     |
|    5 | Robert     | Black     | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester      |
|    6 | Linda      | Green     | 1987-07-30 | 1996-01-04 | 4322.78 | New York  | Tester      |
|    7 | David      | Larry     | 1990-12-31 | 1998-02-12 | 7897.78 | New York  | Manager     |
|    8 | James      | Cat       | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester      |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>

EXECUTE dynamic SQL command

mysql>
mysql>
mysql> CREATE TABLE Employee(
    ->     id            int,
    ->     first_name    VARCHAR(15),
    ->     last_name     VARCHAR(15),
    ->     start_date    DATE,
    ->     end_date      DATE,
    ->     salary        FLOAT(8,2),
    ->     city          VARCHAR(10),
    ->     description   VARCHAR(15)
    -> );
Query OK, 0 rows affected (0.03 sec)
mysql>
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->              values (1,"Jason",    "Martin",  "19960725",  "20060725", 1234.56, "Toronto",  "Programmer");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(2,"Alison",   "Mathews",  "19760321", "19860221", 6661.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(3,"James",    "Smith",    "19781212", "19900315", 6544.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(4,"Celia",    "Rice",     "19821024", "19990421", 2344.78, "Vancouver","Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(5,"Robert",   "Black",    "19840115", "19980808", 2334.78, "Vancouver","Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(6,"Linda",    "Green",    "19870730", "19960104", 4322.78,"New York",  "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(7,"David",    "Larry",    "19901231", "19980212", 7897.78,"New York",  "Manager");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date,   salary,  City,       Description)
    ->               values(8,"James",    "Cat",     "19960917",  "20020415", 1232.78,"Vancouver", "Tester");
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> select * from Employee;
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| id   | first_name | last_name | start_date | end_date   | salary  | city      | description |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
|    1 | Jason      | Martin    | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto   | Programmer  |
|    2 | Alison     | Mathews   | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester      |
|    3 | James      | Smith     | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester      |
|    4 | Celia      | Rice      | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager     |
|    5 | Robert     | Black     | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester      |
|    6 | Linda      | Green     | 1987-07-30 | 1996-01-04 | 4322.78 | New York  | Tester      |
|    7 | David      | Larry     | 1990-12-31 | 1998-02-12 | 7897.78 | New York  | Manager     |
|    8 | James      | Cat       | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester      |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql>
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE PROCEDURE myProc (in_id VARCHAR(1000))
    -> BEGIN
    ->   SET @sql=CONCAT(
    ->       "SELECT first_name,last_name
    ">          FROM employee
    ">         WHERE id=",in_id);
    ->    PREPARE s1 FROM @sql;
    ->    EXECUTE s1;
    ->    DEALLOCATE PREPARE s1;
    -> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql> call myProc(1);
+------------+-----------+
| first_name | last_name |
+------------+-----------+
| Jason      | Martin    |
+------------+-----------+
1 row in set (0.00 sec)
Query OK, 0 rows affected (0.02 sec)
mysql> drop procedure myProc;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>