Example: MERGE Updating a Primary Index - Analytics Database - Teradata Vantage

SQL Data Manipulation Language

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2024-04-05
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lifecycle
latest
Product Category
Teradata Vantage™

You cannot update primary index or partitioning column unless the source is a valid single-row subquery.

Suppose you have created the following tables:

     CREATE TABLE t1 (
       x1 INTEGER,
       y1 INTEGER,
       z1 INTEGER)
     PRIMARY INDEX(x1);

     CREATE TABLE t2 (
       x2 INTEGER,
       y2 INTEGER,
       z2 INTEGER)
     PRIMARY INDEX(x2)
     UNIQUE INDEX(y2);

The following case is valid:

     MERGE INTO t1
       USING (SELECT x2, y2, z2
              FROM t2
              WHERE y2=10) AS s
       ON x1=10 AND y1=20
     WHEN MATCHED THEN
       UPDATE SET x1=10
     WHEN NOT MATCHED THEN
       INSERT (y2, z2, x2);

The following case is not valid because while the subquery guarantees a single row, no constant in specified in the ON clause equality condition, so you cannot update the primary index as this request attempts to do:

     MERGE INTO t1
       USING (SELECT x2,y2, z2
              FROM t2
              WHERE y2=10) AS s
       ON x1=y2 AND y1=z2
     WHEN MATCHED THEN
       UPDATE SET x1=10
     WHEN NOT MATCHED THEN
       INSERT (y2, z2, x2);