Help Center/ GaussDB(DWS)/ Tool Guide/ DSC/ SQL Syntax Migration Reference/ Teradata Syntax Migration/ Functions and Operators/ Query Migration Operators/ ALIAS
Updated on 2024-07-19 GMT+08:00
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ALIAS

ALIAS is supported by all databases. In Teradata, an ALIAS can be referred in SELECT and WHERE clauses of the same statement where the alias is defined. Since ALIAS is not supported in SELECT and WHERE clauses in the target, it is replaced by the defined value/expression.

  • The comparison operators LT, LE, GT, GE, EQ, and NE must not be used as TABLE alias or COLUMN alias.
  • The tool supports column ALIAS. If the ALIAS is the same as the column name, the ALIAS is specified only for that column and not for other columns in the table. In the following example, the column name DATA_DT conflicts with the alias DATA_DT, which is not supported by the tool. 
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    SELECT DATA_DT,DATA_INT AS DATA_DT FROM KK WHERE DATA_DT=DATE;

Input: ALIAS

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SELECT
          expression1 (
               TITLE 'Expression 1'
          ) AS alias1
          ,CASE
               WHEN alias1 + Cx >= z
               THEN 1
               ELSE 0
          END AS alias2
     FROM
          tab1
     WHERE
          alias1 = y
;

Output: tdMigrateALIAS = FALSE

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SELECT
          expression1 AS alias1
          ,CASE
               WHEN alias1 + Cx >= z
               THEN 1
               ELSE 0
          END AS alias2
     FROM
          tab1
     WHERE
          alias1 = y
;

Output: tdMigrateALIAS = TRUE

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SELECT
          expression1 AS alias1
          ,CASE
               WHEN expression1 + Cx >= z
               THEN 1
               ELSE 0
          END AS alias2
     FROM
          tab1
     WHERE
          expression1 = y
;