A guide to the SQL Update Statement

A guide to the SQL Update Statement
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To update a record in a table you use the UPDATE statement.

Be careful. You can update all records of the table or just a few. Use the WHERE condition to specify which records do you want to update. It is possible to update one or more columns at a time. The syntax is:

UPDATE table_name
SET column1 = value1, 
    column2 = value2, ...
WHERE condition;

Here is an example updating the Name of the record with Id 4:

UPDATE Person
SET Name = “Elton John”
WHERE Id = 4;

You can also update columns in a table by using values from other tables. Use JOIN clause to get data from multiple tables. The syntax is:

UPDATE table_name1
SET table_name1.column1 = table_name2.columnA
    table_name1.column2 = table_name2.columnB
FROM table_name1
JOIN table_name2 ON table_name1.ForeignKey = table_name2.Key

Here is an example updating Manager of all records:

UPDATE Person
SET Person.Manager = Department.Manager
FROM Person
JOIN Department ON Person.DepartmentID = Department.ID