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How do you MERGE records in SQL?
The MERGE statement basically works as separate INSERT, UPDATE, and DELETE statements all within the same statement. You specify a “Source” record set and a “Target” table and the JOIN condition between the two.
What is MERGE command in SQL?
The MERGE statement in SQL is a very popular clause that can handle inserts, updates, and deletes all in a single transaction without having to write separate logic for each of these. The MERGE statement tries to compare the source table with the target table based on a key field and then do some of the processing.
Is MERGE DDL or DML?
This statement is a convenient way to combine multiple operations. It lets you avoid multiple INSERT , UPDATE , and DELETE DML statements. MERGE is a deterministic statement. That is, you cannot update the same row of the target table multiple times in the same MERGE statement.
Is delete a DDL command?
DROP and TRUNCATE are DDL commands, whereas DELETE is a DML command. DELETE operations can be rolled back (undone), while DROP and TRUNCATE operations cannot be rolled back.
How do I find duplicate records in Oracle SQL?
How to Find Duplicate Records in Oracle
- SELECT * FROM fruits;
- SELECT fruit_name, color, COUNT(*) FROM fruits GROUP BY fruit_name, color;
- SELECT fruit_name, color, COUNT(*) FROM fruits GROUP BY fruit_name, color HAVING COUNT(*) > 1;
How does the MERGE statement in SQL Server work?
Rows with LocationID 1 and 3 are matched in the target and source table as per the join condition and the value of LocationName in the target was updated with the value of LocationName in the source table for both rows.
What does not matched mean in SQL server merge?
For the matching rows, you need to update the rows columns in the target table with values from the source table. NOT MATCHED: these are the rows from the source table that does not have any matching rows in the target table. In the diagram, they are shown as orange.
Can a MERGE statement update the same table multiple times?
A MERGE statement cannot UPDATE/DELETE the same row of the target table multiple times. Refine the ON clause to ensure a target row matches at most one source row, or use the GROUP BY clause to group the source rows.”
Are there rows that match the merge condition?
MATCHED: these are the rows that match the merge condition. In the diagram, they are shown as blue. For the matching rows, you need to update the rows columns in the target table with values from the source table.