UPDATE

The UPDATE statement is used to modify existing records in a table. You can update one or more columns with new values, or even use subqueries to update values based on other tables.

Basic UPDATE Syntax

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

Examples

Updating a Single Column

Consider the following TableA:

id	num	num2	name
1	2	4	Hello
1	9	5	World
3	4	7	Great
4	7	10	Job

To update the id column for all rows in TableA, you can use the following query:

UPDATE TableA SET id = 2;

The resulting TableA would look like this:

id	num	num2	name
2	2	4	Hello
2	9	5	World
2	4	7	Great
2	7	10	Job

Updating with a Condition

If you want to update only specific rows that meet a certain condition, you can use the WHERE clause. For example, to update the id column only for the row with num = 9:

UPDATE TableA SET id = 4 WHERE num = 9;

Updating with a Subquery

You can also use a subquery in the UPDATE statement to update a column based on other table's values. For example, to update the num2 column in TableA with the rank column value from TableB where the num column values match, and the num = 7:

UPDATE TableA SET num2 = (SELECT rank FROM TableB WHERE num = TableA.num) WHERE num = 7;

Updating Based on the Result of Another Query

You can update a column based on the result of another query. For example, to update the num2 column in TableA with the rank column value from TableB where the num column values match, and the num is the minimum num in TableA:

UPDATE TableA SET num2 = (SELECT rank FROM TableB WHERE num = TableA.num) WHERE num = (SELECT MIN(num) FROM TableA);

Not Supported Features

• Using JOIN in an UPDATE statement is not supported.
• Updating a table using compound identifiers (e.g., ErrTestTable.id = 1) is not supported.
• Updating a non-existent table will result in a TableNotFound error.
• Updating a non-existent column will result in a ColumnNotFound error.