ÆóÒµSQLÃæÊÔÌâ
Ò»£®A¡¢B¡¢C¡¢DËÄÕűíµÄ½á¹¹Ïàͬ£¬ £¨¶«´ó½ðÖÇ£©
°üº¬Ëĸö×ֶΣºid¡¢name¡¢address¡¢age
a£©.´æÔÚÓÚA±íÖУ¬²»´æÔÚÓÚB±íºÍD±íµÄÊý¾Ý
b£©.½«²»ÊôÓÚ±íDµÄµ«ÊÇÔÚ±íAÖеÄÊý¾Ý²åÈëµ½±íBÖÐÈ¥
¶þ.
±íAºÍ±íB£¬½á¹¹Ò»Ö£¬ÓÐÊý¾ÝÈô¸É¡££¨ÑÇÐſƼ¼£©
ÏÖÕÒ³öB±íÖУ¬B±íÓëA±íÈý¸ö¶ÔÓ¦×Ö¶ÎÖÐÓÐÁ½¸ö¶ÔÓ¦×Ö¶ÎÏàµÈµÄ¼Ç¼¡£
ÀýÈ磺
±íA
COL1 COL2 COL3
1 10 100
2 20 200
3 30 300
4 40 400
±íB
COL1 COL2 COL3
1 20 1
2 20 222
1 102 111
3 30 300
9 40 400
Êä³ö£º
col1 col2 col3
2 20 222
3 30 300
9 40 400
Èý. ¸ø³öÒ»¸ö±íµÄÊý¾ÝÈçÏ£¨ÈýÐǵç×Ó£©
ÈÕÆÚ µç·Ñ
6ÔÂ1ÈÕ 60
6ÔÂ2ÈÕ 34
6ÔÂ3ÈÕ
6ÔÂ4ÈÕ
µÈ
Ìõ¼þ£º3Èյĵç·Ñ=1ÈÕ+2ÈÕ
4Èյĵç·Ñ=2ÈÕ+3ÈÕ
дsqlÓï¾ä£¬×îÖÕÏÔʾ³öÁùÔÂËùÓеç·Ñ
ËÄ£®´´½¨Á½ÕÅ±í£ºstudent¡¢grades£¨ÎÄ˼´´Ð£©
student±í
grades±í
1£©Ê¹ÓÃSQLÓï¾ä´´½¨ÈçͼµÄÁ½Õűí
student : id¡¢name¡¢class¡¢grade
grade : id¡¢name¡¢chinese¡¢math¡¢English
Î壮д³öÒ»ÌõsqlÓï¾ä£º
È¡³ö±íAÖеÚ31µ½µÚ40¼Ç¼£¨SQLServer, ÒÔ×Ô¶¯Ôö³¤µÄID×÷ΪÖ÷¼ü, ×¢Ò⣺ID¿ÉÄܲ»ÊÇÁ¬ÐøµÄ¡££©
£¨Áª´´£©