How to use conditional statements to execute (or bypass) chunks of code in Hive/SQL?

I know how to use conditional statements in Hive to assign values to variables, for example

CASE WHEN expression = condition1 THEN result1
WHEN expression = condition2 THEN result2
...
ELSE result
END;


Now I would like to use conditional statements to decide whether to execute a chunk of code. When I try to apply the above, it fails. For example,

CASE WHEN (expression = condition1 or expression = condition2)
THEN
CREATE TABLE table1;
CREATE TABLE table2;
CREATE TABLE table3;
END;


I get an error message FAILED: ParseException line 5:0 cannot recognize input near 'CASE' 'WHEN' '('.

FAILED: ParseException line 5:0 cannot recognize input near 'CASE' 'WHEN' '('

Is it possible to use conditional statements to execute/bypass chunks of code?
Thanks!

from init_table insert into first_table select ... insert into second_table select ...

2 Answers
2

You cannot use conditional statements in Hive with DDL https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL

I suggest you to create empty tables then make multiple inserts, e.g.,

from source_table
insert overwrite
table first_table
select column1, column2
where column1 = 'something'
insert overwrite
table second_table
select column1, column2
where column1 = 'something_else'
;


More info about inserts here, about creating tables here

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