I am doing a merge where a string exists in my target table.
To this I want to concat a new delta value which is a ; separated string list in my
WHEN MATCHED .... UPDATE clause
eg.
set TARGET_VALUE = 'abc';
set DELTA = 'abc;def';
After concat:
OUTPUT should be abc;def;
select CONCAT($TARGET_VALUE,';', $DELTA);
Gives me abc;abc;def.
Is there a way to achieve this inline without converting the strings to Array and following: How to concatenate arrays in Snowflake with distinct values? ?
I want to avoid creating a custom function or snippet and check if there is an inline way to achieve this.
I wrote a UDF to achieve this, but is there an inline way ?
set TARGET_VALUE = 'xyhx;abc';
set DELTA = 'abc;def';
select string_distinct_concat($TARGET_VALUE, $DELTA);
// Distinct Concatenate
create or replace function string_distinct_concat(target varchar, delta varchar)
returns variant
language javascript
comment = 'Returns a distinct concatenation of two strings'
as
$$
if (TARGET == null) {
return DELTA
}
if (DELTA == null) {
return TARGET
}
const target_array = TARGET.split(';');
const delta_array = DELTA.split(';');
const set = new Set([...target_array,...delta_array])
return [...set].join(';');
$$
;
CodePudding user response:
Here is one approach using split_to_table and listagg with distinct.
set TARGET_VALUE = 'abc';
set DELTA = 'abc;def';
select listagg(distinct t.value,';') final_val from
table(split_to_table(concat($DELTA,';',$TARGET_VALUE),';')) t;
FINAL_VAL |
---|
abc;def |
Set target with partial string as in DELTA. This should be included in final output.
set TARGET_VALUE = 'ab';
select listagg(distinct t.value,';') final_val from
table(split_to_table(concat($DELTA,';',$TARGET_VALUE),';')) t;
FINAL_VAL |
---|
abc;def;ab |
Here are two approaches for NULL handling, I prefer CTE approach
with var_cte as
(
select column1 as var from values
($DELTA),
($TARGET_VALUE)
), no_null_cte as
(
select t.value from var_cte, table(split_to_table(var,';')) t
)select listagg(distinct value,';') from no_null_cte;
Using NVL -
select listagg(distinct t.value,';') from table
(
split_to_table(concat(nvl($DELTA,''),';',nvl($TARGET_VALUE,'')),';')) t
where t.value != '';