Access几个小技巧总结

1、查询Access中的表名称 
select name from MSysObjects where type=1 and flags=0 MSysObjects 

2、几个查询结果Union All时，当使用了无表查询时，提示“查询输入必须包含至少一个表或查询” 
　　也就是说在Access里，这样的查询，并不能出想要的结果 
　　select 'wallimn' 
    union all 
    select name from MSysObjects 

　　这时可以建一个一行一列的表，比如效仿Oracle，建一个DUAL，从这个表里查些不相干的东西就行了。 
　　select 'wallimn' from dual 
    union all 
    select name from MSysObjects 

3、Access多表外联查询（三个或以上）的写法 

SELECT * FROM (aa LEFT JOIN bb ON aa.a = bb.a ) LEFT JOIN cc ON cc.a = bb.a; 

注意：在使用join语句查询时，如果有加多个On条件，必须用括号括起来，如： 

SELECT * FROM (aa LEFT JOIN bb ON aa.a=bb.a) LEFT JOIN cc ON(bb.a=cc.a and bb.b=cc.b) 

其他例子可以参考： 

(1)、SELECT * FROM URL as a LEFT OUTER JOIN MobileAfter as b ON a.URL = b.URL 

(2)、SELECT * FROM (URL as a LEFT OUTER JOIN MobileAfter as b ON a.URL= b.URL) LEFT OUTER JOIN MobileBefore as c ONc.URL=a.URL 

(3)、SELECT * INTO Ttable1 FROM ((((URL as a 
LEFT OUTER JOIN MobileAfter as b ON a.URL=b.URL) 
LEFT OUTER JOIN MobileBefore as c ON c.URL=a.URL) 
LEFT OUTER JOIN TeleCOM as d ON d.URL=a.URL) 
LEFT OUTER JOIN UniCOM as e ON e.URL=a.URL)