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UPDATE

The UPDATE command in SQL is used to modify the existing records in a table. This command is useful when you need to update existing data within a database.

Here are important points to remember before updating records in SQL:

  • The WHERE clause in the UPDATE statement specifies which records to modify. If you omit the WHERE clause, all records in the table will be updated!

  • Be careful when updating records in SQL. If you inadvertently run an UPDATE statement without a WHERE clause, you will rewrite all the data in the table.

SQL UPDATE Syntax​

Here is a basic syntax of SQL UPDATE command:

UPDATE table_name
SET column1 = value1, column2 = value2...., columnN = valueN
WHERE [condition];

In this syntax:

  • table_name: Specifies the table where you want to update records.
  • SET: This keyword is used to set the column values.
  • column1, column2... columnN: These are the columns of the table that you want to change.
  • value1, value2... valueN: These are the new values that you want to assign for your columns.
  • WHERE: This clause specifies which records need to be updated. It selects records based on one or more conditions.

SQL UPDATE Example​

Let's assume we have the following Students table:

StudentIDFirstNameLastNameAge
1JohnDoe20
2JaneSmith22
3BobJohnson23

And we want to update the Age of the student with StudentID as 2. We can use the UPDATE command as follows:

UPDATE Students
SET Age = 23
WHERE StudentID = 2;

After executing the above SQL command, the Age of the student with StudentID 2 will be updated to 23.

StudentIDFirstNameLastNameAge
1JohnDoe20
2JaneSmith23
3BobJohnson23