Question

Can you please help me to understand where is the problem?

SELECT mz_t_NaznExec.p_Services FROM mz_t_NaznExec

Above script returns recordset where record with p_Services = 200000000000115 not exists

SELECT mz_t_Services.p_ID from mz_t_Services

Above script returns recordset where record with id = 200000000000115 exists
But this query returns no record

SELECT mz_t_Services.p_ID from mz_t_Services where mz_t_Services.p_ID not in(SELECT mz_t_NaznExec.p_Services FROM mz_t_NaznExec)

I am using MSSQL
EDIT:
Both p_ID and p_Services data types ara bigint

Answer 1

Are there any NULLs in mz_t_NaznExec.p_Services? “NOT IN” will always fail if there is even one NULL in the resultset.