![]() WHERE EXISTS (SELECT * FROM table_2 t2 WHERE t2.date = t1. IN is very problematic when date could potentially be NULL so if you don't want to use a JOIN then I would suggest EXISTS. WHERE t1.date IN (SELECT date FROM table_2) If you want to keep the way you had it which typically EXISTS would be better than IN but to to use IN you need an actual SELECT statement in your where. SELECT GENERATE_SERIES('', '', '1 day'::INTERVAL) AS date I prefer INNER JOIN over IN or Exists so here is a syntax that should work with a JOIN: WITH table_1 AS ( WHERE date IN table_2 is not valid because you never actually reference a value/column from table_2. Note however that you had a second syntax issue in regards to your WHERE statement. In terms of your actual query this syntax should work in PostgreSql, Oracle, and sql-server, well the later typically you will proceed WITH with a semicolon ( WTIH), but that is because typically sql-server folks (myself included) don't end previous statements which need to be ended prior to a CTE being defined. To overcome this result, we can use COALESCE to make NULL values return 0 in this particular case.Per the other comments the second Common Table Expression is preceded by a comma not a WITH statement so WITH cte1 AS (SELECT.) postgres=# SELECT amount - discount as "final bill" FROM sales Ĥ. This is because any arithmetic performed on a NULL value will result in NULL. If we try to perform subtract a value in the "discount" column from a value in the "amount" column, the last row will return a NULL value. Insert data into table “sales”: postgres=# INSERT INTO salesģ. Create a table “sales” using the CREATE TABLE command: postgres=# CREATE TABLE salesĢ. You can use other functions as parameters inside the COALESCE function: postgres=# SELECT coalesce(nvl(null,199),least(8,null),avg(9.9)) Ī helpful application of the COALESCE function is to prevent NULL values from appearing in query results. ![]() Because these parameters are not of the same type, the signature of the function is invalid, and so produces and error.ĥ. The first parameter is an integer, and the now() function returns a timestamp with time zone. If the data types of the parameters don't match, this will produce an error: postgres=# SELECT coalesce(1,now(),null) ĮRROR: COALESCE types integer and timestamp with time zone cannot be matched There are multiple NULLs in this expression, but because the first non-NULL value was reached on the third parameter, all remaining values were disregarded.Ĥ. Here is how it interprets multiple NULL values: postgres=# SELECT coalesce(null,null, 1, 2, 3, null, 4) The COALESCE function found a NULL value in the first parameter, so it continued to the second parameter, which was not NULL, so that parameter's value was returned.ģ. Here is how COALESCE works when a NULL value is the first parameter: postgres=# select coalesce (null,1,2) The COALESCE function finds the first non-NULL expression at the start, so it will always produce the same result regardless of what the remaining parameters contain.Ģ. Here is how COALESCE works with a non-NULL value for the first parameter: postgres=# select coalesce (1,null,2)
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