SQL TutorialLesson 12Free preview

SQL Update

This lesson is part of SQL · All levels

Summary

UPDATE is used to change the value of an existing row in a table. Always use the WHERE clause so that only the target line changes; without WHERE, the entire line in the table is updated. You can change several columns at once by using a comma to separate them.

Key points

Structure: UPDATE the table SET column = the WHERE value of the condition;
Without WHERE, all the lines on the table would change.
Several columns are changed at once: SET column1 = v1, column2 = v2.
The new value can be an expression, for example price = price * 1.1.
You'd better check with the same SELECT before running the big update.

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