Either the SQL-variable-name or label can be used to qualify other SQL variable names in the statement.
If SQL-variable-name is specified, then it should be used to qualify any other SQL variable names in the statement when debugging the SQL function, SQL procedure, or SQL trigger.
Each expression in the select list must have a name. If an expression is not a simple column name, the AS clause must be used to name the expression. If the AS clause is specified, that name is used for the variable and must be unique.
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