Atomic INSERT/SELECT in HSQLDB

问题

I have the following hsqldb table, in which I map UUIDs to auto incremented IDs:

SHORT_ID (BIG INT, PK, auto incremented) | UUID (VARCHAR, unique)

Create command:

CREATE TABLE mytable (SHORT_ID BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY, UUID VARCHAR(36) UNIQUE)

In order to add new pairs concurrently, I want to use the atomic MERGE INTO statement. So my (prepared) statement looks like this:

MERGE INTO mytable USING (VALUES(CAST(? AS VARCHAR(36)))) AS v(x) ON mytable.UUID = v.x WHEN NOT MATCHED THEN INSERT VALUES v.x

When I execute the statement (setting the placeholder correctly), I always get a

Caused by: org.hsqldb.HsqlException: row column count mismatch

Could you please give me a hint, what is going wrong here?

Thanks in advance.

回答1:

Epilogue

I reported this behavior as a bug, and it is today (2010-05-25) fixed in the hsqldb SVN repository, per hsqldb-Bugs-2989597. (Thanks, hsqldb!)

Updated Answer

Neat one! Here's what I got to work under HSQLDB 2.0.0rc9, which supports the syntax and the error message you posted:

MERGE INTO mytable
   USING (SELECT 'a uuid' FROM dual) AS v(x) -- my own "DUAL" table
   ON (mytable.UUID = v.x)
   WHEN NOT MATCHED THEN INSERT
     VALUES (NULL, x)                        -- explicit NULL for "SHORT_ID" :(

Note, I could not convince 2.0.0rc9 to accept ... THEN INSERT (UUID) VALUES (x), which is IIUC a perfectly acceptable and clearer specification than the above. (My SQL knowledge is hardly compendious, but this looks like a bug to me.)

Original Answer

You appear to be INSERTing a single value (a 1-tuple) into a table with more than one column. Perhaps you can modify the end of your statement to read:

... WHEN NOT MATCHED INSERT ("UUID") VALUES (v.x)

回答2:

I got same problems but solve in few minutes.

Its occur when datavalues and table structure are not same.Add explicit (NULL) in your empty column value.

Like i created table

TestCase table:

ID TESTCASEID DESCRIPTION

but your insertion statement you donot want to add any description for any testcase description then you have to explicite in insertion statement you have to set null value for description

来源：https://stackoverflow.com/questions/2609996/atomic-insert-select-in-hsqldb

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sql

merge

hsqldb