Question

access与delphi标准表达式中数据类型不匹配

ADOQuery1.SQL.Text:='select * from unit where Class='''+UnitClass+''' and (Emap_X-'+inttostr(X)+')*(Emap_X-'+inttostr(X)+')+(Emap_Y-'+inttostr(Y)+')*(Emap_Y-'+inttostr(Y)+')<='+inttostr(R*R);

Answer 1

数据库中如果这字符型数据，在SQL语句加：quotedstr（STRING）
如：mStr:='insert into order (field1,field2,field3,field4) '
+'values('+quotedstr(edit1.text)+quotedstr(edit2.text) +quotedstr(edit3.text)+quotedstr(edit4.text)+')'

还有就是你的：where 后，各个条件，加上括号试下。也就是AND前的条件，加个括号民，AND后的条件，再加个括号

Answer 2

试试这个：
ADOQuery1.SQL.Text:='select * from unit where (Class='''+UnitClass+''' ) and ((Emap_X-'+inttostr(X)+')*(Emap_X-'+inttostr(X)+')+(Emap_Y-'+inttostr(Y)+')*(Emap_Y-'+inttostr(Y)+')<='+inttostr(R*R));