UPDATE

The UPDATE statement overwrites the values of map entries that match the condition in a given WHERE clause. However, you cannot update keys in map entries.

note

This statement is not atomic. If it fails, a part of the rows might be updated and another part might remain unchanged.

Syntax Summary

This code block is a quick reference with all the parameters that you can use with the UPDATE statement.

See some practical examples.

sql

UPDATE table_name [ [ AS ] alias ]
SET { column_name = expression } [, ...]
[ WHERE condition ]

Parameters

The UPDATE statement accepts the following required parameters.

Parameter	Description	Example
column_name	The name of column to set value for.	Update Columns by Name
expression	The value to assign. Can be a literal, parameter, or an expression from other column's values.	Update Columns by Name
WHERE condition	An optional clause that, if given, indicates the conditions that rows must satisfy to be updated. condition is an expression that is evaluated for each row. If the expression is true, the row is selected. If there's no WHERE clause, all rows are updated.	Update Columns by Name

Examples

This section lists some example SQL queries that show you how to use the UPDATE statement.

Update Columns by Name

You can overwrite the values in columns by name, using the SET clause.

For example, in a map that contains Employee objects as values with the following structure:

Name	Type
startDate	INT
amount	INT
title	VARCHAR
department	VARCHAR

You can update the values of the Employee.department field:

sql

UPDATE employees
SET department = 'engineering'
WHERE title LIKE '%developer%';

Whether you can access nested fields like this in objects depends on how your map entries are serialized:

• For Java objects (Serializable, DataSerializable, IdentifiedDataSerializable), you must add the object's class to the classpath of the member you are sending the query to.
• For Portable / Compact objects, you do not need to add the object's class to the classpath of the member, unless you want to use parameterized queries to compare one object against another.