Finding part of string and extracting data between delimiter using BigQuery SQL-CodePudding

I have a column like this:

String_to_Extract
A~S1_B~S2_C~S11
A~S1_B~S3_C~S12
C~S13_A~S11_B~S4

The part before the "~" should be the column name. The part after the "~" should be the row value. This is separated by a "_" . Therefore, the result should look like this:

String_to_Extract	A	B	C
A~S1_B~S2_C~S11	S1	S2	S11
A~S1_B~S3_C~S12	S1	S3	S12
C~S13_A~S11_B~S4	S11	S4	S13

Here is my approach:

SELECT
String_to_Extract,
SUBSTRING(String_to_Extract, INSTR(Advertiser, "A~") 2, ?) AS A,
SUBSTRING(String_to_Extract, INSTR(Advertiser, "B~") 2, ?) AS B,
SUBSTRING(String_to_Extract, INSTR(Advertiser, "C~") 2, ?) AS C,
From Table

How do I get the part between the ~ and next _ for each column?

Would be glad about help!

CodePudding user response：

One approach uses REGEXP_EXTRACT:

SELECT
    REGEXP_EXTRACT(String_to_Extract, r"(?:^|_)A~([^_] )") AS A,
    REGEXP_EXTRACT(String_to_Extract, r"(?:^|_)B~([^_] )") AS B,
    REGEXP_EXTRACT(String_to_Extract, r"(?:^|_)C~([^~] )") AS C
FROM yourTable;

CodePudding user response：

Consider below approach (BigQuery)

select * from (
  select String_to_Extract, col_val[offset(0)] as col, col_val[offset(1)] as val
  from your_table, unnest(split(String_to_Extract, '_')) kv,
  unnest([struct(split(kv, '~') as col_val)])
)
pivot (any_value(val) for col in ('A', 'B', 'C'))

If applied to sample data in your question - output is