columnName

In many places in the SQL syntax, you can represent the name of a column by qualifying it with a tableName or correlationName.

In some situations, you cannot qualify a columnName with a tableName or a correlationName, but must use a simpleColumnName instead. Those situations are:

Creating a table (CREATE TABLE statement)
Specifying updatable columns in a cursor
In a column's correlation name in a SELECT expression (see selectExpression)
In a column's correlation name in a tableExpression (see tableExpression)

You cannot use correlationNames for updatable columns; using correlationNames in this way will cause an SQL exception. For example:

SELECT c11 AS col1, c12 AS col2, c13 FROM t1 FOR UPDATE of c11,c13

In this example, the correlationName col1 FOR c11 is not permitted because c11 is listed in the FOR UPDATE list of columns. You can use the correlationName FOR c12 because it is not in the FOR UPDATE list.

Syntax

[ { tableName | correlationName } . ] SQL92Identifier

Example

-- C.Country is a columnName qualified with a correlationName.
SELECT C.Country
FROM APP.Countries C