Add documentation for the LPAD and RPAD OQL functions by passalaqua · Pull Request #11190 · mendix/docs

passalaqua · 2026-05-12T13:01:13Z

~~Should be added in 11.11.0~~

Changed to 11.12.0 in a196c91

katarzyna-koltun-mx · 2026-05-13T09:18:54Z

Awaiting 11.11 release.

passalaqua · 2026-05-13T09:27:49Z

Awaiting 11.11 release.

Just FYI, this still requires approval from the team and for the implementation story to be finalised.

katarzyna-koltun-mx · 2026-05-13T09:29:51Z

Got it, will wait for the go ahead.

…e pad_expression multi-character alert

pijuskri · 2026-05-20T14:46:52Z

Approved by team for technical review

MarkvanMents

Thanks for the PR. I have a few questions:

MarkvanMents · 2026-05-21T12:39:24Z

+
+#### expression
+
+`expression` specifies the expression of type `string` to pad.


Any special behavior for NULL? For Trim it returns NULL but does this just return a whole load of pad_expression?

They just return null if either the expression or length are null. If the padding pattern is null, it is usually null (HSQLDB is the exception and throws an error).

And if expression is the empty string or the length is zero, then Oracle returns null, but other databases return the empty string.

And if the padding pattern is the empty string, then Oracle and MariaDB return null, HSQLDB uses the space character, MySQL returns the empty string, and other databases return the original string. It's kind of a mess and I suppose those are cases where things can be described as "it's database dependent", so I didn't add to this page.

Is it worth noting that this edge case behavior depends on the database and that the customer should test them on their configuration? I'm not sure that all our users would think about this, or might raise questions about it.

MarkvanMents · 2026-05-21T12:40:07Z

+`length_expression` specifies the length of the resulting string. The expression must be of type `integer` or `long`
+
+{{% alert color="info" %}}
+If `length_expression` is smaller than the length of `expression`, this function truncates it. This behavior is database specific.


Truncates the right side, even though we are doing LPAD?

Weirdly, yes. We were just as confused when implementing. The only exception is HSQLDB, which does the right thing, but possibly by accident given how special it is.

Thanks for the answer. We've said that it's database specific, so let's just leave it like that, rather than trying to give an actual answer.

MarkvanMents · 2026-05-21T12:42:48Z

+```sql
+SELECT LPAD('hello', 10, 'x') AS padded FROM Sales.Order
+```
+
+| padded     |
+|:-----------|
+| xxxxxhello |
+


Is it worth an example with a string pad_expression?

SELECT LPAD('hello', 10, 'abc') AS padded FROM Sales.Order

Probably a good idea. I can write it as part of the same query (shorter page) or as a separate example (clearer). Which one do you prefer?

Let's go for the clearer one.
(I need to review this page and split it up anyhow if we want it to be translatable - another few lines won't make any difference)

MarkvanMents · 2026-05-21T12:44:40Z

+`length_expression` specifies the length of the resulting string. The expression must be of type `integer` or `long`
+
+{{% alert color="info" %}}
+If `length_expression` is smaller than the length of `expression`, this function truncates it.


Still normal truncation - so the same as LPAD?

OK - should we add the note about it being database specific to encourage the user to test it?

RPAD is consistent. It's only LPAD that behaves differently in HSQLDB and other dbs.

MarkvanMents · 2026-05-21T12:45:25Z

 | 0.33         | 3.33333333 |
 | 1.17         | 1.17142857 |

+### RPAD {#rpad-function}


Same comments as for LPAD

MarkvanMents · 2026-05-21T12:50:07Z

+| padded     |
+|:-----------|
+|      hello |


This looks wrong when built. May have to think around this (  would work - but still difficult to see that it is space padded rather than right justified)

)

I suppose we can change the query to

SELECT '|' + LPAD('hello', 10) + '|' AS padded FROM Sales.Order

The resulting string would be | hello|. Would we render it correctly with spaces?

We could also just render the result as

·····hello

Or something similar and indicate · represents a whitespace.

Good idea. Let's do that. using the · character so it is clear we didn't mean .

MarkvanMents

Thanks for your answers. I've had a quick look.
Let me know if you have any questions, or would like me to draft any changes.
Mark

MarkvanMents · 2026-05-27T11:45:53Z

+
+#### expression
+
+`expression` specifies the expression of type `string` to pad.


Is it worth noting that this edge case behavior depends on the database and that the customer should test them on their configuration? I'm not sure that all our users would think about this, or might raise questions about it.

MarkvanMents · 2026-05-27T11:47:39Z

+`length_expression` specifies the length of the resulting string. The expression must be of type `integer` or `long`
+
+{{% alert color="info" %}}
+If `length_expression` is smaller than the length of `expression`, this function truncates it. This behavior is database specific.


Thanks for the answer. We've said that it's database specific, so let's just leave it like that, rather than trying to give an actual answer.

MarkvanMents · 2026-05-27T11:50:33Z

+| padded     |
+|:-----------|
+|      hello |


Good idea. Let's do that. using the · character so it is clear we didn't mean .

MarkvanMents · 2026-05-27T11:51:55Z

+```sql
+SELECT LPAD('hello', 10, 'x') AS padded FROM Sales.Order
+```
+
+| padded     |
+|:-----------|
+| xxxxxhello |
+


Let's go for the clearer one.
(I need to review this page and split it up anyhow if we want it to be translatable - another few lines won't make any difference)

MarkvanMents · 2026-05-27T11:53:51Z

+`length_expression` specifies the length of the resulting string. The expression must be of type `integer` or `long`
+
+{{% alert color="info" %}}
+If `length_expression` is smaller than the length of `expression`, this function truncates it.


OK - should we add the note about it being database specific to encourage the user to test it?

…amples

katarzyna-koltun-mx self-assigned this May 12, 2026

katarzyna-koltun-mx added the 11.11 label May 13, 2026

MarkvanMents added the Needs language review label May 18, 2026

MarkvanMents self-requested a review May 18, 2026 08:44

MarkvanMents self-assigned this May 18, 2026

pijuskri suggested changes May 20, 2026

View reviewed changes

Comment thread content/en/docs/refguide/modeling/domain-model/oql/oql-expression-syntax.md Outdated

Comment thread content/en/docs/refguide/modeling/domain-model/oql/oql-expression-syntax.md

passalaqua added 2 commits May 20, 2026 16:44

Add documentation for the LPAD and RPAD OQL functions

bc21da1

Change introduction date for oql padding functions to 11.12 and remov…

a196c91

…e pad_expression multi-character alert

passalaqua force-pushed the dat/feature/pad-functions branch from 5bc8c1d to a196c91 Compare May 20, 2026 14:44

MarkvanMents added 11.12 LTS and removed 11.11 labels May 21, 2026

MarkvanMents reviewed May 21, 2026

View reviewed changes

MarkvanMents reviewed May 27, 2026

View reviewed changes

Add more examples to L/RPAD and use · for the space character in ex…

b3249c0

…amples

passalaqua force-pushed the dat/feature/pad-functions branch from 7973784 to b3249c0 Compare May 27, 2026 13:40

passalaqua added 2 commits May 27, 2026 15:41

Re-add info about optional parameter in padding functions

18ced86

Add null/empty values specifications to oql padding functions

237e220


		#### expression

		`expression` specifies the expression of type `string` to pad.

Conversation

passalaqua commented May 12, 2026 • edited by MarkvanMents Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

katarzyna-koltun-mx commented May 13, 2026

Uh oh!

passalaqua commented May 13, 2026

Uh oh!

katarzyna-koltun-mx commented May 13, 2026

Uh oh!

Uh oh!

Uh oh!

pijuskri commented May 20, 2026

Uh oh!

MarkvanMents left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

MarkvanMents left a comment

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

passalaqua commented May 12, 2026 •

edited by MarkvanMents

Loading