我有两个SQL语句,我希望它们的性能相似,但实际上SQL1使用了0.065秒,而SQL2使用了超过10秒,总共只有8,000条记录。有人能帮我解释一下吗?如何优化SQL2?SQL 1: job_id, REGEXP_COUNT(JOB_Description, '(ABC|DEF)([[:digit:]]){5}') as occurrences where TO_
这里是SQL,我在这里提取employee_name列中的数据,并用于报告。with A4 as select 'govinda j/INDIA_MH/9975215025' as employee_name from dualselect employee_name_',1,1)+1,INSTR(A4.employee_name,'/',1,2)-INSTR(A4.employee_name