Boolean Operators AND OR in SQL

This step-by-step guide explains how to update command in SQL. It covers the required setup, the main actions, and the checks that help prevent common problems.

UPDATE TEN_BANG
SET cot1 = gtri1, cot2 = gtri2., cotN = gtriN
WHERE [DIEU_KIEN];

If you want to use more than one condition in WHERE, don't forget the AND and OR operators we already know about in the previous SQL.

In this example, we will use the UPDATE command to update the DIACHI field for staff with ID of 3, from Hanam to Hanoi.

+----+----------+-----+-----------+---------+ | ID | TEN | TUOI| DIACHI | LUONG | +----+----------+-----+-----------+---------+ | 1 | Thanh | 24 | Haiphong | 2000.00 | | 2 | Loan | 26 | Hanoi | 1500.00 | | 3 | Nga | 24 | Hanam | 2000.00 | | 4 | M?nh | 29 | Hue | 6500.00 | | 5 | Huy | 28 | Hatinh | 8500.00 | | 6 | Cao | 23 | HCM | 4500.00 | | 7 | Lam | 29 | Hanoi | 15000.00| +----+----------+-----+-----------+---------+ 

The statement will look like this:

SQL > UPDATE NHANVIEN SET DIACHI = 'Hanoi' WHERE ID = 3 ;

The original NHANVIEN table will become as follows:

+----+----------+-----+-----------+---------+ | ID | TEN | TUOI| DIACHI | LUONG | +----+----------+-----+-----------+---------+ | 1 | Thanh | 24 | Haiphong | 2000.00 | | 2 | Loan | 26 | Hanoi | 1500.00 | | 3 | Nga | 24 | Hanoi | 2000.00 | | 4 | M?nh | 29 | Hue | 6500.00 | | 5 | Huy | 28 | Hatinh | 8500.00 | | 6 | Cao | 23 | HCM | 4500.00 | | 7 | Lam | 29 | Hanoi | 15000.00| +----+----------+-----+-----------+---------+

If you want to edit all the values in the DIACHI and LUONG columns in the NHANVIEN table, you do not need to use the WHERE clause, just use the UPDATE command as shown below.

SQL > UPDATE NHANVIEN SET DIACHI = 'Hanoi' , LUONG = 10000.00 ;

Now the NHANVIEN board will become:

+----+----------+-----+-----------+---------+ | ID | TEN | TUOI| DIACHI | LUONG | +----+----------+-----+-----------+---------+ | 1 | Thanh | 24 | Hanoi |10000.00 | | 2 | Loan | 26 | Hanoi |10000.00 | | 3 | Nga | 24 | Hanoi |10000.00 | | 4 | M?nh | 29 | Hanoi |10000.00 | | 5 | Huy | 28 | Hanoi |10000.00 | | 6 | Cao | 23 | Hanoi |10000.00 | | 7 | Lam | 29 | Hanoi |10000.00 | +----+----------+-----+-----------+---------+

The UPDATE command in SQL is also quite easy to use, right?

In the next section, we will learn about the DELETE query in SQL.

Next lesson: DELETE command in SQL

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