How can I use column reference in REGEXP_REPLACE in Oracle? - database

Question

My script looks like this :
SELECT
regexp_replace(column1,'"resId":([^"]+?)..','"resId":column2,"')
FROM
table;
Here, I need to replace resId value in column1 by value from column2.

Answer 1

It is hard to tell without the sample data and expected output what you exactly want.
It appears you are expecting to transform a pattern like this - "resId":Value1,"otherid":othervalue
Please note I took into consideration that a key value pair of
"resID":value exists in the data and there is a separator ( a space or a comma) between such key-value pairs.
(,|$) indicates a comma separator or end of line after the value. You may change this to contain any separator in your data that distinguishes it from other combinations. If there is no such thing and the data is purer than this, you should care to describe it clearly by editing your question, which may help us to provide you a proper solution.
SQL Fiddle
Query:
SELECT column1,
column2,
regexp_replace(column1,'"resId":[^"]+(,|$)','"resId":' || column2 || '\1') as replaced
FROM t
Results:
| COLUMN1 | COLUMN2 | REPLACED |
|-------------------------------------|---------|-------------------------------------|
| "resId":Value1,"otherid":othervalue | Value2 | "resId":Value2,"otherid":othervalue |
| "otherid":othervalue,"resId":Value1 | Value2 | "otherid":othervalue,"resId":Value2 |

Answer 2

Concatenate the column2 value into your replacement string:
SELECT regexp_replace(
column1,
'"resId":([^"]+?),"','"resId":' || column2 || ',"'
)
FROM table;
However, if you data is well-formed JSON and the "resId" value will be a simple literal (not an array or an object) then you can use a regular expression that would parse this like:
'("resId":)(null|true|false|(-?0|[1-9]\d*)(\.\d*)?([eE][+-]?\d+)?|"(\\["\/bfrnt]|\\u\d{4}|[^"\/'||CHR(8)||CHR(9)|| CHR(10)||CHR(12)||CHR(13)||'])*")'
SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE table_name ( column1, column2 ) AS
SELECT '{"resId":null}', 1 FROM DUAL UNION ALL
SELECT '{"resId":true}', 2 FROM DUAL UNION ALL
SELECT '{"resId":false}', 3 FROM DUAL UNION ALL
SELECT '{"resId":123}', 4 FROM DUAL UNION ALL
SELECT '{"resId":""}', 5 FROM DUAL UNION ALL
SELECT '{"resId":"\r\n"}', 6 FROM DUAL UNION ALL
SELECT '{"resId":"test"}', 7 FROM DUAL UNION ALL
SELECT '{"resId":"' || CHR(13) || CHR(10) || '"}', 8 FROM DUAL;
Query 1:
SELECT column1,
column2,
regexp_replace(
column1,
'("resId":)(null|true|false|(-?0|[1-9]\d*)(\.\d*)?([eE][+-]?\d+)?|"(\\["\/bfrnt]|\\u\d{4}|[^"\/'||CHR(8)||CHR(9)|| CHR(10)||CHR(12)||CHR(13)||'])*")',
'\1' || column2
) As repl
FROM table_name
Results:
| COLUMN1 | COLUMN2 | REPL |
|------------------|---------|----------------|
| {"resId":null} | 1 | {"resId":1} |
| {"resId":true} | 2 | {"resId":2} |
| {"resId":false} | 3 | {"resId":3} |
| {"resId":123} | 4 | {"resId":4} |
| {"resId":""} | 5 | {"resId":5} |
| {"resId":"\r\n"} | 6 | {"resId":6} |
| {"resId":"test"} | 7 | {"resId":7} |
| {"resId":" | 8 | {"resId":" | -- Note: not well-formed JSON
| "} | | "} | -- so did not get matched.