# Sql tag expression

**URL:** <https://forum.inductiveautomation.com/t/sql-tag-expression/16876>\
**Category:** Ignition\
**Created:** [February 5, 2018, 5:43pm UTC](https://forum.inductiveautomation.com/t/sql-tag-expression/16876 "2018-02-05T17:43:06Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Julio.Bautista](https://avatars.discourse-cdn.com/v4/letter/j/3bc359/32.png) [@Julio.Bautista](https://forum.inductiveautomation.com/u/Julio.Bautista)\
**Post date:** [February 5, 2018, 5:43pm UTC](https://forum.inductiveautomation.com/t/sql-tag-expression/16876/1 "2018-02-05T17:43:07Z")

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Would I be able to do this within a sql expression for example:  
select \* from(select top 1 pname FROM sqlth\_partitions order by end\_time desc)  
in order to make searching through a history tag dynamic

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**Author:** ![bfuson](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/bfuson/32/4597_2.png) [@bfuson](https://forum.inductiveautomation.com/u/bfuson)\
**Post date:** [February 5, 2018, 10:02pm UTC](https://forum.inductiveautomation.com/t/sql-tag-expression/16876/2 "2018-02-05T22:02:41Z")

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It sounds possible. What’s stopping you?

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<div class="post-metadata">

**Author:** ![Julio.Bautista](https://avatars.discourse-cdn.com/v4/letter/j/3bc359/32.png) [@Julio.Bautista](https://forum.inductiveautomation.com/u/Julio.Bautista)\
**Post date:** [February 6, 2018, 12:25pm UTC](https://forum.inductiveautomation.com/t/sql-tag-expression/16876/3 "2018-02-06T12:25:19Z")

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[quote=“Julio.Bautista, post:1, topic:16876”]  
select \* from(select top 1 pname FROM sqlth\_partitions order by end\_time desc)  
[/quote

well when I try to run it on the sql query browser on ignition I get this error  
 ![](https://us1.discourse-cdn.com/inductiveautomation/original/2X/5/54ba6d68b693a3fea1178e72cb0edde88e1a441a.png)

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<div class="post-metadata">

**Author:** ![JordanCClark](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/jordancclark/32/83362_2.png) [@JordanCClark](https://forum.inductiveautomation.com/u/JordanCClark)\
**Post date:** [February 6, 2018, 1:01pm UTC](https://forum.inductiveautomation.com/t/sql-tag-expression/16876/4 "2018-02-06T13:01:16Z")

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> [@Julio.Bautista](#):
>
> select \* from(select top 1 pname FROM sqlth\_partitions order by end\_time desc)

You will need to alias the subquery.

```auto

select * from (select top 1 pname FROM sqlth_partitions order by end_time desc) subquery1

```

[https://www.techonthenet.com/sql\_server/subqueries.php](https://www.techonthenet.com/sql_server/subqueries.php)

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<div class="post-metadata">

**Author:** ![Kraenbring](https://avatars.discourse-cdn.com/v4/letter/k/f4b2a3/32.png) [@Kraenbring](https://forum.inductiveautomation.com/u/Kraenbring)\
**Post date:** [February 9, 2018, 7:34pm UTC](https://forum.inductiveautomation.com/t/sql-tag-expression/16876/5 "2018-02-09T19:34:21Z")

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While you do need to alias a sub-query to make it work, this query isn’t going to return what you’re looking for. The top level query only returns a subset of the sub-query (if that makes sense).

What it seems like you’re trying to do is select all the history data for the last partition that was created. For that you’d need to do a dynamic sql statements.

declare @stmt nvarchar(250)  
select top 1 @stmt = 'select \* from ’ + pname FROM sqlth\_partitions order by end\_time desc

exec sp\_executesql @stmt