A SQL statement typically used to `UPDATE` records when they exist and `INSERT` them when they do not.

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31
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1answer
20k views

MERGE a subset of the target table

I am trying to use a MERGE statement to insert or delete rows from a table, but I only want to act on a subset of those rows. The documentation for MERGE has a pretty strongly worded warning: It ...
3
votes
2answers
2k views

Can I optimize this MERGE statement?

I am attempting a single column merge between two tables. The first table (VisitorSession) has 40,000,000 rows. The second (ShoppingCart) has 9,000,000 rows. In my development environment, the query ...
0
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2answers
976 views

How to insert or update using single query?

I have a table test having columns id which primary key and auto incremented and name. I want to insert a new record if annd only if there are no records.For example input is id=30122 and name =john ...