UNION

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Combines results from multiple SELECT statements.

UNION DISTINCT removes duplicate rows, while UNION ALL does not remove them. UNION is equivalent to UNION DISTINCT.

Syntax

SELECT ...
UNION [ALL | DISTINCT] SELECT ...
[UNION [ALL | DISTINCT] SELECT ...]

Remarks

The first and all subsequent SELECT statements must select the same number of columns.
UNION statements are converted into nested sub-select queries by the query processor.
The maximum depth of nested sub-select queries is 40. Beyond this the UNION statements are converted to TABLE, allowing you to write up to 337 statements (0-336).

Examples

SQL

SELECT * FROM table_a UNION ALL SELECT * FROM table_b;
SELECT * FROM table_a UNION SELECT * FROM table_b;

SQL

SELECT * FROM id_t UNION ALL SELECT * FROM id_t2;

 +------+----------------------------------------------------------------------------+
 | a    | b                                                                          |
 +------+----------------------------------------------------------------------------+
 |    1 | 0xE82C75FA86974BE7903270F4353D865C                                         |
 |    1 | 0x31343865306665352D666666322D346363362D383634622D313838303637313135653236 |
 +------+----------------------------------------------------------------------------+

Last modified: March 31, 2025

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Verification instructions

Note: You must install cosign to verify the authenticity of the SingleStore file.

Use the following steps to verify the authenticity of singlestoredb-server, singlestoredb-toolbox, singlestoredb-studio, and singlestore-client SingleStore files that have been downloaded.

You may perform the following steps on any computer that can run cosign, such as the main deployment host of the cluster.

(Optional) Run the following command to view the associated signature files.
Shell
```
curl undefined
```
Download the signature file from the SingleStore release server.
- Option 1: Click the Download Signature button next to the SingleStore file.
- Option 2: Copy and paste the following URL into the address bar of your browser and save the signature file.
- Option 3: Run the following command to download the signature file.
  Shell
```
curl -O undefined
```

After the signature file has been downloaded, run the following command to verify the authenticity of the SingleStore file.

Shell

echo -n undefined |
    cosign verify-blob --certificate-oidc-issuer https://oidc.eks.us-east-1.amazonaws.com/id/CCDCDBA1379A5596AB5B2E46DCA385BC \
      --certificate-identity https://kubernetes.io/namespaces/freya-production/serviceaccounts/job-worker \
      --bundle undefined \
      --new-bundle-format -

Verified OK