我对SELECT FROM WHERE语句有疑问，该查询返回错误的结果。
这是我的桌子，被称为朋友：
+----------+-----------+------------+--------+--------+-------+
| lastname | firstname | callprefix | phone | region | zip |
+----------+-----------+------------+--------+--------+-------+
| Lužný | Bob | 602 | 111222 | OL | 79821 |
| Matyáš | Bob | 773 | 123456 | BR | NULL |
| Strouhal | Fido | 300 | 343434 | ZL | 76701 |
| Přikryl | Tom | 581 | 010101 | PL | 72000 |
| Černý | Franta | 777 | 000999 | OL | 79801 |
| Zavadil | Olda | 911 | 111311 | OL | 79604 |
| Berka | Standa | 604 | 111234 | ZL | 72801 |
| Vlcik | BbB | 736 | 555444 | KV | 35210 |
+----------+-----------+------------+--------+--------+-------+
这是我的查询。
SELECT * FROM friends WHERE region <= 'z';
我希望具有区域ZL的行应该存在，但不存在。你能告诉我为什么吗？
结果是：
+----------+-----------+------------+--------+--------+-------+
| lastname | firstname | callprefix | phone | region | zip |
+----------+-----------+------------+--------+--------+-------+
| Lužný | Bob | 602 | 111222 | OL | 79821 |
| Matyáš | Bob | 773 | 123456 | BR | NULL |
| Přikryl | Tom | 581 | 010101 | PL | 72000 |
| Černý | Franta | 777 | 000999 | OL | 79801 |
| Zavadil | Olda | 911 | 111311 | OL | 79604 |
| Vlcik | BbB | 736 | 555444 | KV | 35210 |
+----------+-----------+------------+--------+--------+-------+
当我尝试此查询时：
SELECT * FROM friends WHERE region >= 'z';
结果包含region ='ZL'的两行
????
谢谢！
答案 0 :(得分：0)
因为“ ZL”大于“ Z”。 Z只是一个字符，因此只会返回小于Z或具有Z值的值。您要通过此查询尝试实现什么？
答案 1 :(得分：0)
你能告诉我为什么吗？
如果添加区域为object(stdClass)#65 (1) { ["WSI2_RecherchePointRelaisResult"]=> object(stdClass)#64 (11) { ["STAT"]=> string(1) "0" ["PR01"]=> object(stdClass)#56 (8) { ["Num"]=> string(6) "098517" ["LgAdr1"]=> string(31) "LA DIFF " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "RUE COURMONT 18 " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR02"]=> object(stdClass)#5 (8) { ["Num"]=> string(6) "001424" ["LgAdr1"]=> string(31) "BOULANGERIE HUBINON LAMONT " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "67 RUE D ISLY " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR03"]=> object(stdClass)#67 (8) { ["Num"]=> string(6) "072109" ["LgAdr1"]=> string(31) "LES HALLES DE MOULINS " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "40-42 RUE JEAN JAURES " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR04"]=> object(stdClass)#68 (8) { ["Num"]=> string(6) "098428" ["LgAdr1"]=> string(31) "O MARCHE DES BISCOTTES " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "RUE DE MARQUILLIES 33 " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR05"]=> object(stdClass)#69 (8) { ["Num"]=> string(6) "002528" ["LgAdr1"]=> string(31) "MY AUCHAN WAZEMMES " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "14 PLACE NOUVELLE AVENTURE " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR06"]=> object(stdClass)#70 (8) { ["Num"]=> string(6) "005393" ["LgAdr1"]=> string(31) "CAR PRO SERVICES " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "103 RUE BALZAC " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR07"]=> object(stdClass)#71 (8) { ["Num"]=> string(6) "003124" ["LgAdr1"]=> string(31) "IMEDIAPHONE " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "94 RUE RACINE " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR08"]=> object(stdClass)#72 (8) { ["Num"]=> string(6) "002742" ["LgAdr1"]=> string(31) "EPICERIE SUPER 400 " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "364 RUE DU FAUBOURG D ARRAS " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR09"]=> object(stdClass)#73 (8) { ["Num"]=> string(6) "098425" ["LgAdr1"]=> string(31) "AUX DELICES " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "RUE D INKERMANN 26. " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59000" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } ["PR10"]=> object(stdClass)#74 (8) { ["Num"]=> string(6) "002898" ["LgAdr1"]=> string(31) "PHONECOM SERVICES " ["LgAdr2"]=> string(0) "" ["LgAdr3"]=> string(31) "273 RUE PIERRE LEGRAND " ["LgAdr4"]=> string(0) "" ["CP"]=> string(5) "59800" ["Ville"]=> string(26) "LILLE " ["Pays"]=> string(2) "FR" } } }
的记录，并按区域的字母顺序对这些行进行排序，您是否希望foreach($pointsRelais as $value) {
if( is_object($value) && !empty(trim($value->Num)){
var_dump($value->Num); // does'nt work
}
}
在Z之前或之后？显然它将接after而来，因此不符合您的标准。
如果您只想考虑第一个字符，请将其添加到您的条件中：
ZL如果您的数据库设置要求区分大小写，我也将Z明确地用大写字母表示。
答案 2 :(得分：0)
您尝试过吗
SELECT * FROM friends WHERE region <= 'zl';？
从计算机的角度来看，'z' < 'zl'