关于 SQL语句中的 变量的表达方式

Question

 ADOQuery_sbcx.SQL.Text:=' SELECT  yqmc,count(*) FROM [zhxt].[dbo].[sbgl] where left([yqmc],i)='''+Adoquery2.FieldByName('yqmc').value+'''   group by yqmc
 如以上语句，i  是一个变量， 这样直接写是错误的，请问应该如何 表达这个i 变量。是 ‘’+i+‘’  ？？ 好像这样也是错误的

Answer 1

不建议用拼接SQL语句，改用Format函数
ADOQuery_sbcx.SQL.Text:=Format('SELECT  yqmc,count(*) FROM [zhxt].[dbo].[sbgl] where left([yqmc],%d)= %s group by yqmc',[i,QuotedStr(Adoquery2.FieldByName('yqmc').AsString)]);

Answer 2

字符串用QuotedStr，看上去顺眼多了
 ADOQuery_sbcx.SQL.Text:=' SELECT  yqmc,count(*) FROM [zhxt].[dbo].[sbgl] where left([yqmc],i)='+
                                                    QuotedStr(Adoquery2.FieldByName('yqmc').value)+
                                                    '  group by yqmc'

Answer 3

ADOQuery_sbcx.SQL.Text:=' SELECT  yqmc,count(*) FROM [zhxt].[dbo].[sbgl] where left([yqmc],‘+inttostr(i)+')='''+Adoquery2.FieldByName('yqmc').value+'''   group by yqmc

Answer 4

 ADOQuery_sbcx.SQL.Text:=' SELECT  yqmc,count(*) FROM [zhxt].[dbo].[sbgl] ’ + 
                                                   ’ where left([yqmc],'+InttoStr(i) + ')='  + 
                                                   QuotedStr(Adoquery2.FieldByName('yqmc').AsString)+' group by yqmc'