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kdb

KDB How to update column values

I have a table which has column of symbol type like below.

Name Value
First TP_RTD_FRV
Second RF_QWE_FRV
Third KF_FRV_POL

I need to update it as below, wherever I have FRV, I need to replace it with AB_FRV. How to achieve this?

Name Value
First TP_RTD_AB_FRV
Second RF_QWE_AB_FRV
Third KF_AB_FRV_POL
Solution 
  • q)t
name v
---------------
0    TP_RTD_FRV
1    RF_QWE_FRV
2    KF_FRV_POL
3    THIS
4    THAT
q)update `$ssr[;"FRV";"AB_FRV"]each string v from t
name v
------------------
0    TP_RTD_AB_FRV
1    RF_QWE_AB_FRV
2    KF_AB_FRV_POL
3    THIS
4    THAT

    or without using qSQL

    q)@[t;`v;]{`$ssr[;"FRV";"AB_FRV"]each string x}
name v
------------------
0    TP_RTD_AB_FRV
1    RF_QWE_AB_FRV
2    KF_AB_FRV_POL
3    THIS
4    THAT

    Depending on the uniqueness of the data, you might benefit from .Q.fu

    q)t:1000000#t
q)\t @[t;`v;]{`$ssr[;"FRV";"AB_FRV"]each string x}
2343
q)\t @[t;`v;].Q.fu {`$ssr[;"FRV";"AB_FRV"]each string x}
10