[teiid-issues] [JBoss JIRA] (TEIID-5403) Support the use of local variables in client SQL query

[SHI HONG CHIN (JIRA)]

SHI HONG CHIN created TEIID-5403:
------------------------------------

             Summary: Support the use of local variables in client SQL query
                 Key: TEIID-5403
                 URL: https://issues.jboss.org/browse/TEIID-5403
             Project: Teiid
          Issue Type: Enhancement
            Reporter: SHI HONG CHIN
            Assignee: Steven Hawkins


In Microsoft SQL Server, when writing SQL query, I can directly declare and set local variables, and then use it as much as I like in the rest of SQL query.

Example:
{code:java}
DECLARE @PARAM1 VARCHAR(100);
SET @PARAM1 = ?;

SELECT
	<SOME COLUMNS>
FROM TABLEA LEFT OUTER JOIN (
	SELECT
		<SOME COLUMNS>
	FROM TABLEB
	WHERE COLUMN1 = @PARAM1
) T1
WHERE TABLEA.COLUMN2 = @PARAM1
UNION ALL
SELECT
	<SOME COLUMNS>
FROM TABLEC
WHERE TABLEC.COLUMN3 = @PARAM1;
{code}

In above example, "@PARAM1" is the local variable that been used multiple times in the query.

The benefits:
1. In programming, I only need to set the parameter for one time. For example, when using Java PreparedStatement's setString(int parameterIndex, String x) function, I only need to write "statement.setString(1, param1);" instead of writing "statement.setString(1, param1); statement.setString(2, param1); statement.setString(3, param1); ....." to set the same value.
2. I no need to create a procedure.

However, in Teiid, I cannot find anyway to achieve this.

In Teiid, please implement the support of local variables in client SQL query.



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