UNION DISTINCT
Posted rsapaper
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了UNION DISTINCT相关的知识，希望对你有一定的参考价值。
w同结构表读写合并。
1 DROP PROCEDURE IF EXISTS w_ww_amzasin; 2 DELIMITER /w/ 3 CREATE PROCEDURE w_ww_amzasin() 4 BEGIN 5 DECLARE done INT DEFAULT FALSE; 6 DECLARE w_asin VARCHAR(16); 7 DECLARE w_country VARCHAR(6); 8 DECLARE wcur CURSOR FOR 9 SELECT asin,country FROM grab_amzreviews_asins 10 UNION DISTINCT 11 SELECT asin,country FROM grab_amzsimilar_seller_asins 12 UNION DISTINCT 13 SELECT asin,country FROM grab_amzlisting 14 WHERE CONCAT(asin,LOWER(country)) NOT IN 15 (SELECT CONCAT(asin,LOWER(country)) FROM amzasin) ; 16 DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE; 17 18 OPEN wcur; 19 read_loop: LOOP 20 FETCH wcur INTO w_asin,w_country; 21 IF done THEN LEAVE read_loop; 22 END IF; 23 SET @w_nothhtps=‘www.amazon.‘; 24 SET @w_most=CONCAT(LOWER(w_country),‘/product/dp/‘,w_asin); 25 CASE LOWER(w_country) 26 WHEN ‘ca‘ THEN SELECT ‘w‘; 27 WHEN ‘in‘ THEN SELECT ‘w‘; 28 WHEN ‘es‘ THEN SELECT ‘w‘; 29 WHEN ‘it‘ THEN SELECT ‘w‘; 30 WHEN ‘fr‘ THEN SELECT ‘w‘; 31 32 WHEN ‘jp‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 33 WHEN ‘uk‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 34 35 WHEN ‘mx‘ THEN SET @w_most=CONCAT(‘com.‘,@w_most); 36 37 WHEN ‘us‘ THEN SET @w_most=CONCAT(‘com/gp/product/‘,w_asin); 38 ELSE 39 BEGIN 40 END; 41 END CASE; 42 43 SET @w_nothhtps=CONCAT(@w_nothhtps,@w_most); 44 SET @wtmp = CONCAT(‘INSERT INTO amzasin (asin,country,url) VALUES ( "‘,w_asin,‘","‘,w_country,‘","‘,@w_nothhtps,‘")‘); 45 PREPARE stmt FROM @wtmp ; 46 EXECUTE stmt ; 47 DROP PREPARE stmt; 48 END LOOP; 49 CLOSE wcur; 50 END/w/ 51 DELIMITER; 52 CALL w_ww_amzasin( ); 53 54 55 56 DROP PROCEDURE IF EXISTS w_ww_amzasin; 57 DELIMITER /w/ 58 CREATE PROCEDURE w_ww_amzasin() 59 BEGIN 60 DECLARE done INT DEFAULT FALSE; 61 DECLARE w_asin VARCHAR(16); 62 DECLARE w_country VARCHAR(6); 63 DECLARE wcur CURSOR FOR SELECT asin,country FROM grab_amzlisting WHERE CONCAT(asin,LOWER(country)) NOT IN (SELECT CONCAT(asin,LOWER(country)) FROM amzasin ); 64 DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE; 65 66 OPEN wcur; 67 read_loop: LOOP 68 FETCH wcur INTO w_asin,w_country; 69 IF done THEN LEAVE read_loop; 70 END IF; 71 SET @w_nothhtps=‘www.amazon.‘; 72 SET @w_most=CONCAT(LOWER(w_country),‘/product/dp/‘,w_asin); 73 CASE LOWER(w_country) 74 WHEN ‘ca‘ THEN SELECT ‘w‘; 75 WHEN ‘in‘ THEN SELECT ‘w‘; 76 WHEN ‘es‘ THEN SELECT ‘w‘; 77 WHEN ‘it‘ THEN SELECT ‘w‘; 78 WHEN ‘fr‘ THEN SELECT ‘w‘; 79 80 WHEN ‘jp‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 81 WHEN ‘uk‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 82 83 WHEN ‘mx‘ THEN SET @w_most=CONCAT(‘com.‘,@w_most); 84 85 WHEN ‘us‘ THEN SET @w_most=CONCAT(‘com/gp/product/‘,w_asin); 86 ELSE 87 BEGIN 88 END; 89 END CASE; 90 91 SET @w_nothhtps=CONCAT(@w_nothhtps,@w_most); 92 SET @wtmp = CONCAT(‘INSERT INTO amzasin (asin,country,url) VALUES ( "‘,w_asin,‘","‘,w_country,‘","‘,@w_nothhtps,‘")‘); 93 PREPARE stmt FROM @wtmp ; 94 EXECUTE stmt ; 95 DROP PREPARE stmt; 96 END LOOP; 97 CLOSE wcur; 98 END/w/ 99 DELIMITER; 100 CALL w_ww_amzasin( ); 101 102 DROP PROCEDURE IF EXISTS w_ww_amzasin; 103 DELIMITER /w/ 104 CREATE PROCEDURE w_ww_amzasin() 105 BEGIN 106 DECLARE done INT DEFAULT FALSE; 107 DECLARE w_asin VARCHAR(16); 108 DECLARE w_country VARCHAR(6); 109 DECLARE wcur CURSOR FOR SELECT asin,country FROM grab_amzsimilar_seller_asins WHERE CONCAT(asin,LOWER(country)) NOT IN (SELECT CONCAT(asin,LOWER(country)) FROM amzasin ); 110 DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE; 111 112 OPEN wcur; 113 read_loop: LOOP 114 FETCH wcur INTO w_asin,w_country; 115 IF done THEN LEAVE read_loop; 116 END IF; 117 SET @w_nothhtps=‘www.amazon.‘; 118 SET @w_most=CONCAT(LOWER(w_country),‘/product/dp/‘,w_asin); 119 CASE LOWER(w_country) 120 WHEN ‘ca‘ THEN SELECT ‘w‘; 121 WHEN ‘in‘ THEN SELECT ‘w‘; 122 WHEN ‘es‘ THEN SELECT ‘w‘; 123 WHEN ‘it‘ THEN SELECT ‘w‘; 124 WHEN ‘fr‘ THEN SELECT ‘w‘; 125 126 WHEN ‘jp‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 127 WHEN ‘uk‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 128 129 WHEN ‘mx‘ THEN SET @w_most=CONCAT(‘com.‘,@w_most); 130 131 WHEN ‘us‘ THEN SET @w_most=CONCAT(‘com/gp/product/‘,w_asin); 132 ELSE 133 BEGIN 134 END; 135 END CASE; 136 137 SET @w_nothhtps=CONCAT(@w_nothhtps,@w_most); 138 SET @wtmp = CONCAT(‘INSERT INTO amzasin (asin,country,url) VALUES ( "‘,w_asin,‘","‘,w_country,‘","‘,@w_nothhtps,‘")‘); 139 PREPARE stmt FROM @wtmp ; 140 EXECUTE stmt ; 141 DROP PREPARE stmt; 142 END LOOP; 143 CLOSE wcur; 144 END/w/ 145 DELIMITER; 146 CALL w_ww_amzasin( ); 147 148 DROP PROCEDURE IF EXISTS w_ww_amzasin; 149 DELIMITER /w/ 150 CREATE PROCEDURE w_ww_amzasin() 151 BEGIN 152 DECLARE done INT DEFAULT FALSE; 153 DECLARE w_asin VARCHAR(16); 154 DECLARE w_country VARCHAR(6); 155 DECLARE wcur CURSOR FOR SELECT asin,country FROM grab_amzreviews_asins WHERE CONCAT(asin,LOWER(country)) NOT IN (SELECT CONCAT(asin,LOWER(country)) FROM amzasin ); 156 DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE; 157 158 OPEN wcur; 159 read_loop: LOOP 160 FETCH wcur INTO w_asin,w_country; 161 IF done THEN LEAVE read_loop; 162 END IF; 163 SET @w_nothhtps=‘www.amazon.‘; 164 SET @w_most=CONCAT(LOWER(w_country),‘/product/dp/‘,w_asin); 165 CASE LOWER(w_country) 166 WHEN ‘ca‘ THEN SELECT ‘w‘; 167 WHEN ‘in‘ THEN SELECT ‘w‘; 168 WHEN ‘es‘ THEN SELECT ‘w‘; 169 WHEN ‘it‘ THEN SELECT ‘w‘; 170 WHEN ‘fr‘ THEN SELECT ‘w‘; 171 172 WHEN ‘jp‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 173 WHEN ‘uk‘ THEN SET @w_most=CONCAT(‘co.‘,@w_most); 174 175 WHEN ‘mx‘ THEN SET @w_most=CONCAT(‘com.‘,@w_most); 176 177 WHEN ‘us‘ THEN SET @w_most=CONCAT(‘com/gp/product/‘,w_asin); 178 ELSE 179 BEGIN 180 END; 181 END CASE; 182 183 SET @w_nothhtps=CONCAT(@w_nothhtps,@w_most); 184 SET @wtmp = CONCAT(‘INSERT INTO amzasin (asin,country,url) VALUES ( "‘,w_asin,‘","‘,w_country,‘","‘,@w_nothhtps,‘")‘); 185 PREPARE stmt FROM @wtmp ; 186 EXECUTE stmt ; 187 DROP PREPARE stmt; 188 END LOOP; 189 CLOSE wcur; 190 END/w/ 191 DELIMITER; 192 CALL w_ww_amzasin( ); 193 194 195 196 197 198
以上是关于UNION DISTINCT的主要内容，如果未能解决你的问题，请参考以下文章
sql中，只使用union和先union all再distinct，两种方式哪个效率高？
SQL Server 查询：Union vs Distinct union 所有性能