# Need clarification on appending single record using concatenation operator

**URL:** <https://forum.kx.com/t/need-clarification-on-appending-single-record-using-concatenation-operator/15553>\
**Category:** Community Support\
**Tags:** kdb-x\
**Created:** [September 27, 2026, 11:01am UTC](https://forum.kx.com/t/need-clarification-on-appending-single-record-using-concatenation-operator/15553 "2026-09-27T11:01:22Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![vajindarladdad](https://avatars.discourse-cdn.com/v4/letter/v/82dd89/32.png) [@vajindarladdad](https://forum.kx.com/u/vajindarladdad)\
**Post date:** [September 27, 2026, 11:01am UTC](https://forum.kx.com/t/need-clarification-on-appending-single-record-using-concatenation-operator/15553/1 "2026-09-27T11:01:22Z")

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Hi Team,

On [How to work with tables - KDB-X Documentation](https://code.kx.com/kdb-x/how_to/basics/data_structures/tables.html#table-metadata) , we have example of appending single row to a table as below:

t:([] name: `Alice`Bob`Mike; phone: ("555-0101"; "555-0723"; "555-6666"); age: 23 32 22);

t,:(`John; "555-5382"; 40) / append a single row & this works with appends to a list in place

Above example works but why belwo elaborated example does not work.

t:([] name: `Alice`Bob`Mike; phone: ("555-0101"; "555-0723"; "555-6666"); age: 23 32 22);

t: t,(`John; "555-5382"; 40) /This give incorrect result with concat & then assign operation

Can somebody please give explaination on this behaviour with KDB-X ?

Thanks,

Vajindar Laddad

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**Author:** ![pgyorok](https://sea2.discourse-cdn.com/flex002/user_avatar/forum.kx.com/pgyorok/32/128_2.png) [@pgyorok](https://forum.kx.com/u/pgyorok)\
**Post date:** [October 12, 2026, 9:22am UTC](https://forum.kx.com/t/need-clarification-on-appending-single-record-using-concatenation-operator/15553/2 "2026-10-12T09:22:18Z")

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Hi Vajindar,

The behavior of `x,:y` and `x:x,y` are not always the same. For example, `x,:y` supports appending a record from a list while `x,y` doesn't.

More details here:

[Join atoms, lists, dictionaries or tables | Reference | KDB-X and q documentation - KDB-X Documentation](https://code.kx.com/kdb-x/ref/join.html#append)