A first SQL Server essay

1. SUM () in SQL replaces count with

SELECT COUNT (Ondutytime) as the entry from dbo this week. Employeemsg WHERE DATEDIFF (Week,ondutytime,getdate ()) =0

SELECT ISNULL (SUM (1), 0) as the entry from dbo this week. Employeemsg WHERE DATEDIFF (Week,ondutytime,getdate ()) =0

SELECT ISNULL (SUM (Case Time DATEDIFF (Week,ondutytime,getdate ()) =0 then 1 END), 0) as this week the entry from dbo. Employeemsg

2. Database compatibility settings: Select the corresponding database right-click Properties--options--compatibility level--Select the version that needs to be compatible

3. Calculate Percent SELECT CONVERT (VARCHAR,100.0/236*100) + '% '

A first SQL Server essay