{"id":1630,"date":"2022-11-21T22:57:37","date_gmt":"2022-11-21T14:57:37","guid":{"rendered":"https:\/\/qaqaq.top\/?p=1630"},"modified":"2022-11-27T12:40:57","modified_gmt":"2022-11-27T04:40:57","slug":"%e7%b4%a2%e5%bc%95%e7%9a%84%e5%88%86%e7%b1%bb%e3%80%81%e8%a1%a8%e4%b8%ad%e6%b7%bb%e5%8a%a0%e7%b4%a2%e5%bc%95%e7%9a%84%e4%b8%89%e7%a7%8d%e6%96%b9%e5%bc%8f%e3%80%81%e5%88%a0%e9%99%a4%e7%b4%a2%e5%bc%95","status":"publish","type":"post","link":"https:\/\/qaqaq.top\/?p=1630","title":{"rendered":"\u7d22\u5f15\u7684\u5206\u7c7b\u3001\u8868\u4e2d\u6dfb\u52a0\u7d22\u5f15\u7684\u4e09\u79cd\u65b9\u5f0f\u3001\u5220\u9664\u7d22\u5f15\u4e0e\u7d22\u5f15\u65b0\u7279\u6027\uff1a\u964d\u5e8f\u7d22\u5f15\u3001\u9690\u85cf\u7d22\u5f15\u3001\u9002\u5408\u521b\u5efa\u7d22\u5f15\u768411\u79cd\u60c5\u51b51\u3001\u9002\u5408\u521b\u5efa\u7d22\u5f15\u768411\u79cd\u60c5\u51b52\u3001\u4e0d\u9002\u5408\u521b\u5efa\u7d22\u5f15\u76847\u79cd\u60c5\u51b5"},"content":{"rendered":"\n<pre class=\"wp-block-code\"><code># \u7b2c08\u7ae0_\u7d22\u5f15\u7684\u521b\u5efa\u4e0e\u8bbe\u8ba1\u539f\u5219\r\n\r\n# 1. \u7d22\u5f15\u7684\u58f0\u660e\u4e0e\u4f7f\u7528\r\n\r\n# 01-\u7d22\u5f15\u7684\u521b\u5efa\r\n\r\n# \u7b2c1\u79cd\uff1aCREATE TABLE\r\n\r\n# \u9690\u5f0f\u7684\u65b9\u5f0f\u521b\u5efa\u7d22\u5f15\u3002\u5728\u58f0\u660e\u6709\u4e3b\u952e\u7ea6\u675f\u3001\u552f\u4e00\u6027\u7ea6\u675f\u3001\u5916\u952e\u7ea6\u675f\u7684\u5b57\u6bb5\u4e0a\uff0c\u4f1a\u81ea\u52a8\u7684\u6dfb\u52a0\u76f8\u5173\u7684\u7d22\u5f15\r\nCREATE DATABASE dbtest2;\r\n\r\nUSE dbtest2;\r\n\r\nCREATE TABLE dept(\r\n    dept_id INT PRIMARY KEY,\r\n    dept_name VARCHAR(20)\r\n);\r\n\r\nCREATE TABLE emp(\r\n    emp_id INT PRIMARY KEY AUTO_INCREMENT,\r\n    emp_name VARCHAR(20) UNIQUE,\r\n    dept_id INT,\r\n    CONSTRAINT emp_dept_id_fk FOREIGN KEY (dept_id) REFERENCES dept(dept_id)\r\n);\r\n\r\n# \u663e\u5f0f\u7684\u65b9\u5f0f\u521b\u5efa\uff1a\r\n# \u2460\u521b\u5efa\u666e\u901a\u7684\u7d22\u5f15\r\nCREATE TABLE book(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR,\r\n    #\u58f0\u660e\u7d22\u5f15\r\n    INDEX idx_bname(book_name)\r\n);\r\n\r\n# \u901a\u8fc7\u547d\u4ee4\u67e5\u770b\u7d22\u5f15\r\n# \u65b9\u5f0f1\uff1a\r\nSHOW CREATE TABLE book;\r\n\r\n# \u65b9\u5f0f2\uff1a\r\nSHOW INDEX FROM book;\r\n\r\n# \u6027\u80fd\u5206\u6790\u5de5\u5177\uff1aEXPLAIN\r\nEXPLAIN SELECT * FROM book\r\nWHERE book_name = 'mysql\u9ad8\u7ea7';\r\n\r\n# \u2461 \u521b\u5efa\u552f\u4e00\u7d22\u5f15\r\n# \u58f0\u660e\u6709\u552f\u4e00\u7d22\u5f15\u7684\u5b57\u6bb5\uff0c\u5728\u6dfb\u52a0\u6570\u636e\u65f6\uff0c\u8981\u4fdd\u8bc1\u552f\u4e00\u6027\uff0c\u4f46\u662f\u53ef\u4ee5\u6dfb\u52a0null\r\nCREATE TABLE book1(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR,\r\n    #\u58f0\u660e\u7d22\u5f15\r\n    UNIQUE INDEX uk_idx_cmt(comment)\r\n);\r\n\r\nSHOW INDEX FROM book1;\r\n\r\nINSERT INTO book1(book_id,book_name,comment)\r\nVALUES(1,'Mysql\u9ad8\u7ea7','\u9002\u5408\u6709\u6570\u636e\u5e93\u5f00\u53d1\u7ecf\u9a8c\u7684\u4eba\u5458\u5b66\u4e60');\r\n\r\nINSERT INTO book1(book_id,book_name,comment)\r\nVALUES(2,'Mysql\u9ad8\u7ea7',NULL);\r\n\r\nSELECT * FROM book1;\r\n\r\n# \u2462 \u4e3b\u952e\u7d22\u5f15\r\n# \u901a\u8fc7\u5b9a\u4e49\u4e3b\u952e\u7ea6\u675f\u7684\u65b9\u5f0f\u5b9a\u4e49\u4e3b\u952e\u7d22\u5f15\r\nCREATE TABLE book2(\r\n    book_id INT PRIMARY KEY,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR\r\n);\r\n\r\nSHOW INDEX FROM book2;\r\n\r\n#\u901a\u8fc7\u5220\u9664\u4e3b\u952e\u7ea6\u675f\u7684\u65b9\u5f0f\u5220\u9664\u4e3b\u952e\u7d22\u5f15\r\nALTER TABLE book2\r\nDROP PRIMARY KEY;\r\n\r\n# \u2463 \u521b\u5efa\u5355\u5217\u7d22\u5f15\r\nCREATE TABLE book3(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR,\r\n    #\u58f0\u660e\u7d22\u5f15\r\n    UNIQUE INDEX idx_bname(book_name)\r\n);\r\n\r\nSHOW INDEX FROM book3;\r\n\r\n# \u2464 \u521b\u5efa\u8054\u5408\u7d22\u5f15\r\nCREATE TABLE book4(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR,\r\n    #\u58f0\u660e\u7d22\u5f15\r\n    INDEX mul_bid_bname_info(book_id,book_name,info)\r\n);\r\n\r\nSHOW INDEX FROM book4;\r\n\r\n# \u5206\u6790\r\nEXPLAIN SELECT * FROM book4 WHERE book_id = 1001 AND book_name = 'mysql';\r\n\r\nEXPLAIN SELECT * FROM book4 WHERE book_name = 'mysql';\r\n\r\n# \u2465 \u521b\u5efa\u5168\u6587\u7d22\u5f15\r\nCREATE TABLE test4(\r\n    id INT NOT NULL,\r\n    name CHAR(30) NOT NULL,\r\n    age INT NOT NULL,\r\n    info VARCHAR(255),\r\n    FULLTEXT INDEX futxt_idx_info(info(50))\r\n);\r\n\r\nSHOW INDEX FROM test4;\r\n\r\n# \u7b2c2\u79cd\uff1a\u8868\u5df2\u7ecf\u521b\u5efa\u6210\u529f\r\n\r\n# \u2460 ALTER TABLE ... ADD ...\r\n\r\nCREATE TABLE book5(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR\r\n);\r\n\r\nSHOW INDEX FROM book5;\r\n\r\nALTER TABLE book5 ADD INDEX idx_cmt(comment);\r\n\r\nALTER TABLE book5 ADD UNIQUE uk_idx_bname(book_name);\r\n\r\nALTER TABLE book5 ADD INDEX mul_bid_bname_info(book_id,book_name,info);\r\n\r\n# \u2461 CREATE INDEX ... ON ...\r\n\r\nCREATE TABLE book6(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR\r\n);\r\n\r\nSHOW INDEX FROM book6;\r\n\r\nCREATE INDEX idx_cmt ON book6(comment);\r\n\r\nCREATE UNIQUE INDEX uk_idx_bname ON book6(book_name);\r\n\r\nCREATE INDEX mul_bid_bname_info ON book6(book_id,book_name,info);\r\n\r\n# 02-\u7d22\u5f15\u7684\u5220\u9664\r\n\r\nSHOW INDEX FROM book5;\r\n\r\n# \u65b9\u5f0f1\uff1aALTER TABLE ... DROP INDEX ...\r\nALTER TABLE book5\r\n    DROP INDEX idx_cmt;\r\n\r\n# \u65b9\u5f0f2\uff1aDROP INDEX ... ON ...\r\nDROP INDEX uk_idx_bname ON book5;\r\n\r\n# \u6d4b\u8bd5\uff1a\u5220\u9664\u8054\u5408\u7d22\u5f15\u4e2d\u7684\u76f8\u5173\u5b57\u6bb5\uff0c\u7d22\u5f15\u7684\u53d8\u5316\r\nALTER TABLE book5\r\nDROP COLUMN book_name;\r\n\r\nALTER TABLE book5\r\nDROP COLUMN book_id;\r\n\r\nALTER TABLE book5\r\nDROP COLUMN info;\r\n\r\n# 2. MySQL8.0\u7d22\u5f15\u65b0\u7279\u6027\r\n\r\n# 03-MySQL8.0\u65b0\u7279\u6027\r\n\r\n# 1. \u652f\u6301\u964d\u5e8f\u7d22\u5f15\r\n\r\nCREATE TABLE ts1(\r\n    a INT,\r\n    b INT,\r\n    INDEX idx_a_b(a ASC,b DESC)\r\n);\r\n\r\nSHOW CREATE TABLE ts1;\r\n\r\nDELIMITER \/\/\r\n\r\nCREATE PROCEDURE ts_insert()\r\nBEGIN\r\n    DECLARE i INT DEFAULT 1;\r\n    WHILE i &lt; 800\r\n        DO\r\n        INSERT INTO ts1 SELECT RAND()*80000,RAND()*80000;\r\n        SET i = i + 1;\r\n        END WHILE;\r\n    COMMIT;\r\nEND \/\/\r\n\r\nDELIMITER ;\r\n\r\n#\u8c03\u7528\r\nCALL ts_insert();\r\n\r\nSELECT COUNT(*) FROM ts1;\r\n\r\n# \u4f18\u5316\u6d4b\u8bd5\r\nEXPLAIN SELECT * FROM ts1 ORDER BY a,b DESC LIMIT 5;\r\n\r\n# \u4e0d\u63a8\u8350\r\nEXPLAIN SELECT * FROM ts1 ORDER BY a DESC,b DESC LIMIT 5;\r\n\r\n# 2. \u9690\u85cf\u7d22\u5f15\r\n# \u2460 \u521b\u5efa\u8868\u65f6 \u9690\u85cf\u7d22\u5f15\r\n\r\nCREATE TABLE book7(\r\n    book_id INT,\r\n    book_name VARCHAR(100),\r\n    authors VARCHAR(100),\r\n    info VARCHAR(100) ,\r\n    comment VARCHAR(100),\r\n    year_publication YEAR,\r\n    #\u521b\u5efa\u4e0d\u53ef\u89c1\u7684\u7d22\u5f15\r\n    INDEX idx_cmt(comment) INVISIBLE\r\n);\r\n\r\nSHOW INDEX FROM book7;\r\n\r\nEXPLAIN SELECT * FROM book7 WHERE comment = 'mysql....';\r\n\r\n# \u2461 \u521b\u5efa\u8868\u4ee5\u540e\r\nALTER TABLE book7\r\nADD UNIQUE INDEX uk_idx_bname(book_name) INVISIBLE;\r\n\r\nCREATE INDEX idx_year_pub ON book7(year_publication);\r\n\r\nEXPLAIN SELECT * FROM book7 WHERE year_publication = '2022';\r\n\r\n#\u4fee\u6539\u7d22\u5f15\u7684\u53ef\u89c1\u6027\r\nALTER TABLE book7 ALTER INDEX idx_year_pub INVISIBLE;   #\u53ef\u89c1 ---> \u4e0d\u53ef\u89c1\r\n\r\nALTER TABLE book7 ALTER INDEX idx_cmt VISIBLE;      #\u4e0d\u53ef\u89c1 ---> \u53ef\u89c1\r\n\r\n#\u4e86\u89e3\uff1a\u4f7f\u9690\u85cf\u7d22\u5f15\u5bf9\u67e5\u8be2\u4f18\u5316\u5668\u53ef\u89c1\r\n\r\nSELECT @@optimizer_switch;\r\n\r\nSET SESSION optimizer_switch = \"use_invisible_indexes=on\";\r\n\r\nEXPLAIN SELECT * FROM book7 WHERE year_publication = '2022';\r\n\r\n# 3. \u7d22\u5f15\u7684\u8bbe\u8ba1\u539f\u5219\r\n\r\n# 04-\u7d22\u5f15\u7684\u8bbe\u8ba1\u539f\u5219\r\n\r\n# 3.1 \u6570\u636e\u7684\u51c6\u5907\r\n\r\n# \u7b2c1\u6b65\uff1a\u521b\u5efa\u6570\u636e\u5e93\u3001\u521b\u5efa\u8868\r\n\r\nCREATE DATABASE atguigudb1;\r\n\r\nUSE atguigudb1;\r\n\r\n#1.\u521b\u5efa\u5b66\u751f\u8868\u548c\u8bfe\u7a0b\u8868\r\n\r\nCREATE TABLE `student_info` (\r\n    `id` INT(11) AUTO_INCREMENT,\r\n    `student_id` INT NOT NULL,\r\n    `name` VARCHAR(20) DEFAULT NULL,\r\n    `course_id` INT NOT NULL,\r\n    `class_id` INT(11) DEFAULT NULL,\r\n    `create_time` DATETIME DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,\r\n    PRIMARY KEY (`id`)\r\n) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;\r\n\r\nCREATE TABLE `course` (\r\n    `id` INT(11) NOT NULL AUTO_INCREMENT,\r\n    `course_id` INT NOT NULL,\r\n    `course_name` VARCHAR(40) DEFAULT NULL,\r\n    PRIMARY KEY (`id`)\r\n) ENGINE=INNODB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;\r\n\r\n# \u7b2c2\u6b65\uff1a\u521b\u5efa\u6a21\u62df\u6570\u636e\u5fc5\u9700\u7684\u5b58\u50a8\u51fd\u6570\r\n\r\n#\u51fd\u65701\uff1a\u521b\u5efa\u968f\u673a\u4ea7\u751f\u5b57\u7b26\u4e32\u51fd\u6570\r\n\r\nDELIMITER \/\/\r\nCREATE FUNCTION rand_string(n INT)\r\n    RETURNS VARCHAR(255) #\u8be5\u51fd\u6570\u4f1a\u8fd4\u56de\u4e00\u4e2a\u5b57\u7b26\u4e32\r\nBEGIN\r\n    DECLARE chars_str VARCHAR(100) DEFAULT\r\n    'abcdefghijklmnopqrstuvwxyzABCDEFJHIJKLMNOPQRSTUVWXYZ';\r\n    DECLARE return_str VARCHAR(255) DEFAULT '';\r\n    DECLARE i INT DEFAULT 0;\r\n    WHILE i &lt; n DO\r\n        SET return_str =CONCAT(return_str,SUBSTRING(chars_str,FLOOR(1+RAND()*52),1));\r\n        SET i = i + 1;\r\n    END WHILE;\r\n    RETURN return_str;\r\nEND \/\/\r\nDELIMITER ;\r\n\r\nSELECT @@log_bin_trust_function_creators;\r\n\r\nSET GLOBAL log_bin_trust_function_creators = 1;\r\n\r\n#\u51fd\u65702\uff1a\u521b\u5efa\u968f\u673a\u6570\u51fd\u6570\r\n\r\nDELIMITER \/\/\r\nCREATE FUNCTION rand_num (from_num INT ,to_num INT)\r\n    RETURNS INT(11)\r\nBEGIN\r\n    DECLARE i INT DEFAULT 0;\r\n    SET i = FLOOR(from_num +RAND()*(to_num - from_num+1)) ;\r\n    RETURN i;\r\nEND \/\/\r\nDELIMITER ;\r\n\r\n# \u7b2c3\u6b65\uff1a\u521b\u5efa\u63d2\u5165\u6a21\u62df\u6570\u636e\u7684\u5b58\u50a8\u8fc7\u7a0b\r\n\r\n# \u5b58\u50a8\u8fc7\u7a0b1\uff1a\u521b\u5efa\u63d2\u5165\u8bfe\u7a0b\u8868\u5b58\u50a8\u8fc7\u7a0b\r\nDELIMITER \/\/\r\nCREATE PROCEDURE insert_course( max_num INT )\r\nBEGIN\r\n    DECLARE i INT DEFAULT 0;\r\n    SET autocommit = 0; #\u8bbe\u7f6e\u624b\u52a8\u63d0\u4ea4\u4e8b\u52a1\r\n    REPEAT #\u5faa\u73af\r\n        SET i = i + 1; #\u8d4b\u503c\r\n        INSERT INTO course (course_id, course_name ) VALUES\r\n        (rand_num(10000,10100),rand_string(6));\r\n        UNTIL i = max_num\r\n    END REPEAT;\r\n    COMMIT; #\u63d0\u4ea4\u4e8b\u52a1\r\nEND \/\/\r\nDELIMITER ;\r\n\r\n# \u5b58\u50a8\u8fc7\u7a0b2\uff1a\u521b\u5efa\u63d2\u5165\u5b66\u751f\u4fe1\u606f\u8868\u5b58\u50a8\u8fc7\u7a0b\r\nDELIMITER \/\/\r\nCREATE PROCEDURE insert_stu( max_num INT )\r\nBEGIN\r\n    DECLARE i INT DEFAULT 0;\r\n    SET autocommit = 0; #\u8bbe\u7f6e\u624b\u52a8\u63d0\u4ea4\u4e8b\u52a1\r\n    REPEAT #\u5faa\u73af\r\n        SET i = i + 1; #\u8d4b\u503c\r\n        INSERT INTO student_info (course_id, class_id ,student_id ,NAME ) VALUES\r\n        (rand_num(10000,10100),rand_num(10000,10200),rand_num(1,200000),rand_string(6));\r\n        UNTIL i = max_num\r\n    END REPEAT;\r\n    COMMIT; #\u63d0\u4ea4\u4e8b\u52a1\r\nEND \/\/\r\nDELIMITER ;\r\n\r\n# \u7b2c4\u6b65\uff1a\u8c03\u7528\u5b58\u50a8\u8fc7\u7a0b\r\n\r\nCALL insert_course(100);\r\n\r\nSELECT COUNT(*) FROM course;\r\n\r\nCALL insert_stu(1000000);\r\n\r\nSELECT COUNT(*) FROM student_info;\r\n\r\n# 3.2 \u54ea\u4e9b\u60c5\u51b5\u9002\u5408\u521b\u5efa\u7d22\u5f15\r\n\r\n# \u2460 \u5b57\u6bb5\u7684\u6570\u503c\u6709\u552f\u4e00\u6027\u7684\u9650\u5236\r\n\r\n# \u2461 \u9891\u7e41\u4f5c\u4e3a WHERE \u67e5\u8be2\u6761\u4ef6\u7684\u5b57\u6bb5\r\n\r\n# \u67e5\u770b\u5f53\u524dstudent_info\u8868\u4e2d\u7684\u7d22\u5f15\r\nSHOW INDEX FROM student_info;\r\n\r\n#student_id\u5b57\u6bb5\u4e0a\u6ca1\u6709\u7d22\u5f15\u7684\uff1a\r\nSELECT course_id,class_id,name,create_time,student_id\r\nFROM student_info\r\nWHERE student_id = 123110;  #295 ms\r\n\r\n#\u7ed9student_id\u5b57\u6bb5\u6dfb\u52a0\u7d22\u5f15\r\nALTER TABLE student_info\r\nADD INDEX idx_sid(student_id);\r\n\r\n#student_id\u5b57\u6bb5\u4e0a\u6709\u7d22\u5f15\u7684\uff1a\r\nSELECT course_id,class_id,name,create_time,student_id\r\nFROM student_info\r\nWHERE student_id = 123110; #29 ms\r\n\r\n# \u2462 \u7ecf\u5e38 GROUP BY \u548c ORDER BY \u7684\u5217\r\n\r\n# student_id\u5b57\u6bb5\u4e0a\u6709\u7d22\u5f15\u7684\uff1a\r\nSELECT student_id,COUNT(*) AS num\r\nFROM student_info\r\nGROUP BY student_id LIMIT 100;  #44 ms\r\n\r\n#\u5220\u9664idx_sid\u7d22\u5f15\r\nDROP INDEX idx_sid ON student_info;\r\n\r\n# student_id\u5b57\u6bb5\u4e0a\u6ca1\u6709\u7d22\u5f15\u7684\uff1a\r\nSELECT student_id,COUNT(*) AS num\r\nFROM student_info\r\nGROUP BY student_id LIMIT 100;  #370 ms\r\n\r\n#\u518d\u6d4b\u8bd5\uff1a\r\nSHOW INDEX FROM student_info;\r\n\r\n#\u6dfb\u52a0\u5355\u5217\u7d22\u5f15\r\nALTER TABLE student_info\r\nADD INDEX idx_sid(student_id);\r\n\r\nALTER TABLE student_info\r\nADD INDEX idx_cre_time(create_time);\r\n\r\nEXPLAIN SELECT student_id,COUNT(*) AS num FROM student_info\r\nGROUP BY student_id\r\nORDER BY create_time DESC\r\nLIMIT 100;  #6 s 50 ms\r\n\r\n#\u4fee\u6539sql_mod\r\n\r\nSELECT @@sql_mode;\r\n\r\n# ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION\r\n\r\nSET @@sql_mode = 'STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_ENGINE_SUBSTITUTION'\r\n\r\n# \u6dfb\u52a0\u8054\u5408\u7d22\u5f15\r\nALTER TABLE student_info\r\nADD INDEX idx_sid_cre_time(student_id,create_time DESC);\r\n\r\nEXPLAIN SELECT student_id,COUNT(*) AS num FROM student_info\r\nGROUP BY student_id\r\nORDER BY create_time DESC\r\nLIMIT 100;  #370 ms\r\n\r\n#\u518d\u8fdb\u4e00\u6b65\uff1a\r\nALTER TABLE student_info\r\nADD INDEX idx_cre_time_sid(create_time DESC,student_id);\r\n\r\nDROP INDEX idx_sid_cre_time ON student_info;\r\n\r\nEXPLAIN SELECT student_id,COUNT(*) AS num FROM student_info\r\nGROUP BY student_id\r\nORDER BY create_time DESC\r\nLIMIT 100;  #2 s 915 ms\r\n\r\n# \u2463 UPDATE\u3001DELETE \u7684 WHERE \u6761\u4ef6\u5217\r\n\r\nSHOW INDEX FROM student_info;\r\n\r\nUPDATE student_info SET student_id = 10002\r\nWHERE NAME = 'akldjkwfafaewe231ds'; #740 ms\r\n\r\n#\u6dfb\u52a0\u7d22\u5f15\r\nALTER TABLE student_info\r\nADD INDEX idx_name(name);\r\n\r\nUPDATE student_info SET student_id = 10002\r\nWHERE NAME = 'akldjkwfafaewe231ds'; #4 ms\r\n\r\n# \u2464 DISTINCT \u5b57\u6bb5\u9700\u8981\u521b\u5efa\u7d22\u5f15\r\n\r\n# \u2465 \u591a\u8868 JOIN \u8fde\u63a5\u64cd\u4f5c\u65f6\uff0c\u521b\u5efa\u7d22\u5f15\u6ce8\u610f\u4e8b\u9879\r\n\r\n# \u9996\u5148\uff0c \u8fde\u63a5\u8868\u7684\u6570\u91cf\u5c3d\u91cf\u4e0d\u8981\u8d85\u8fc7 3 \u5f20 \uff0c\u56e0\u4e3a\u6bcf\u589e\u52a0\u4e00\u5f20\u8868\u5c31\u76f8\u5f53\u4e8e\u589e\u52a0\u4e86\u4e00\u6b21\u5d4c\u5957\u7684\u5faa\u73af\uff0c\u6570\u91cf\u7ea7\u589e\u957f\u4f1a\u975e\u5e38\u5feb\uff0c\u4e25\u91cd\u5f71\u54cd\u67e5\u8be2\u7684\u6548\u7387\u3002\r\n\r\n# \u5176\u6b21\uff0c \u5bf9 WHERE \u6761\u4ef6\u521b\u5efa\u7d22\u5f15 \uff0c\u56e0\u4e3a WHERE \u624d\u662f\u5bf9\u6570\u636e\u6761\u4ef6\u7684\u8fc7\u6ee4\u3002\u5982\u679c\u5728\u6570\u636e\u91cf\u975e\u5e38\u5927\u7684\u60c5\u51b5\u4e0b\uff0c\u6ca1\u6709 WHERE \u6761\u4ef6\u8fc7\u6ee4\u662f\u975e\u5e38\u53ef\u6015\u7684\u3002\r\n\r\n# \u6700\u540e\uff0c \u5bf9\u7528\u4e8e\u8fde\u63a5\u7684\u5b57\u6bb5\u521b\u5efa\u7d22\u5f15 \uff0c\u5e76\u4e14\u8be5\u5b57\u6bb5\u5728\u591a\u5f20\u8868\u4e2d\u7684 \u7c7b\u578b\u5fc5\u987b\u4e00\u81f4 \u3002\u6bd4\u5982 course_id \u5728student_info \u8868\u548c course \u8868\u4e2d\u90fd\u4e3a int(11) \u7c7b\u578b\uff0c\u800c\u4e0d\u80fd\u4e00\u4e2a\u4e3a int \u53e6\u4e00\u4e2a\u4e3a varchar \u7c7b\u578b\u3002\r\n\r\nEXPLAIN SELECT s.course_id,name,s.student_id,c.course_name\r\nFROM student_info s JOIN course c\r\nON s.course_id = c.course_id\r\nWHERE name = '462eed7ac6e791292a79';    #23 ms\r\n\r\nDROP INDEX idx_name ON student_info;\r\n\r\nEXPLAIN SELECT s.course_id,name,s.student_id,c.course_name\r\nFROM student_info s JOIN course c\r\nON s.course_id = c.course_id\r\nWHERE name = '462eed7ac6e791292a79';    #251 ms\r\n\r\n# \u2466 \u4f7f\u7528\u5217\u7684\u7c7b\u578b\u5c0f\u7684\u521b\u5efa\u7d22\u5f15\r\n\r\n# \u2467 \u4f7f\u7528\u5b57\u7b26\u4e32\u524d\u7f00\u521b\u5efa\u7d22\u5f15\r\n\r\n# \u521b\u5efa\u4e00\u5f20\u5546\u6237\u8868\uff0c\u56e0\u4e3a\u5730\u5740\u5b57\u6bb5\u6bd4\u8f83\u957f\uff0c\u5728\u5730\u5740\u5b57\u6bb5\u4e0a\u5efa\u7acb\u524d\u7f00\u7d22\u5f15\r\n# CREATE TABLE shop(address VARCHAR(120) NOT NULL);\r\n# ALTER TABLE shop ADD INDEX (address(12));\r\n\r\n# \u95ee\u9898\u662f\uff0c\u622a\u53d6\u591a\u5c11\u5462\uff1f\u622a\u53d6\u5f97\u591a\u4e86\uff0c\u8fbe\u4e0d\u5230\u8282\u7701\u7d22\u5f15\u5b58\u50a8\u7a7a\u95f4\u7684\u76ee\u7684\uff1b\u622a\u53d6\u5f97\u5c11\u4e86\uff0c\u91cd\u590d\u5185\u5bb9\u592a\u591a\uff0c\r\n# \u5b57\u6bb5\u7684\u6563\u5217\u5ea6(\u9009\u62e9\u6027)\u4f1a\u964d\u4f4e\u3002\u600e\u4e48\u8ba1\u7b97\u4e0d\u540c\u7684\u957f\u5ea6\u7684\u9009\u62e9\u6027\u5462\uff1f\r\n\r\n# \u5148\u770b\u4e00\u4e0b\u5b57\u6bb5\u5728\u5168\u90e8\u6570\u636e\u4e2d\u7684\u9009\u62e9\u5ea6\uff1a\r\n# SELECT COUNT(DISTINCT address) \/ COUNT(*) FROM shop;\r\nSELECT COUNT(DISTINCT name) \/ COUNT(*) FROM student_info;\r\n\r\n# \u901a\u8fc7\u4e0d\u540c\u957f\u5ea6\u53bb\u8ba1\u7b97\uff0c\u4e0e\u5168\u8868\u7684\u9009\u62e9\u6027\u5bf9\u6bd4\uff1a\r\n# \u516c\u5f0f:\r\n# COUNT(DISTINCT LEFT(\u5217\u540d, \u7d22\u5f15\u957f\u5ea6)) \/ COUNT(*)\r\n# \u4f8b\u5982\uff1a\r\n# SELECT COUNT(DISTINCT LEFT(name,10)) \/ COUNT(*) AS sub10,    -- \u622a\u53d6\u524d10\u4e2a\u5b57\u7b26\u7684\u9009\u62e9\u5ea6\r\n# COUNT(DISTINCT LEFT(name,15)) \/ COUNT(*) AS sub11,   -- \u622a\u53d6\u524d15\u4e2a\u5b57\u7b26\u7684\u9009\u62e9\u5ea6\r\n# COUNT(DISTINCT LEFT(name,20)) \/ COUNT(*) AS sub12,   -- \u622a\u53d6\u524d20\u4e2a\u5b57\u7b26\u7684\u9009\u62e9\u5ea6\r\n# COUNT(DISTINCT LEFT(name,25)) \/ COUNT(*) AS sub13    -- \u622a\u53d6\u524d25\u4e2a\u5b57\u7b26\u7684\u9009\u62e9\u5ea6\r\n# FROM shop;\r\n\r\nSELECT COUNT(DISTINCT LEFT(name,2)) \/ COUNT(*) AS sub10,\r\nCOUNT(DISTINCT LEFT(name,3)) \/ COUNT(*) AS sub11,\r\nCOUNT(DISTINCT LEFT(name,4)) \/ COUNT(*) AS sub12,\r\nCOUNT(DISTINCT LEFT(name,5)) \/ COUNT(*) AS sub13\r\nFROM student_info;\r\n\r\n# \u2468 \u533a\u5206\u5ea6\u9ad8(\u6563\u5217\u6027\u9ad8)\u7684\u5217\u9002\u5408\u4f5c\u4e3a\u7d22\u5f15\r\n\r\n# \u516c\u5f0f\uff1a\r\n# SELECT COUNT(DISTINCT a) \/ COUNT(*) FROM t1;\r\n\r\n# \u2469 \u4f7f\u7528\u6700\u9891\u7e41\u7684\u5217\u653e\u5230\u8054\u5408\u7d22\u5f15\u7684\u5de6\u4fa7\r\n\r\nSELECT *\r\nFROM student_info\r\nWHERE student_id = 10013 AND course_id = 100;\r\n\r\n# \u2492\u5728\u591a\u4e2a\u5b57\u6bb5\u90fd\u8981\u521b\u5efa\u7d22\u5f15\u7684\u60c5\u51b5\u4e0b\uff0c\u8054\u5408\u7d22\u5f15\u4f18\u4e8e\u5355\u503c\u7d22\u5f15\r\n\r\n# 3.3 \u9650\u5236\u7d22\u5f15\u7684\u6570\u76ee\r\n\r\n# \u5728\u5b9e\u9645\u5de5\u4f5c\u4e2d\uff0c\u6211\u4eec\u4e5f\u9700\u8981\u6ce8\u610f\u5e73\u8861\uff0c\u7d22\u5f15\u7684\u6570\u76ee\u4e0d\u662f\u8d8a\u591a\u8d8a\u597d\uff0c\u6211\u4eec\u9700\u8981\u9650\u5236\u6bcf\u5f20\u8868\u4e0a\u7684\u7d22\u5f15\u6570\u91cf\uff0c\r\n# \u5efa\u8bae\u5355\u5f20\u8868\u7d22\u5f15\u6570\u91cf\u4e0d\u8d85\u8fc76\u4e2a\u3002\r\n\r\n#3.4 \u54ea\u4e9b\u60c5\u51b5\u4e0d\u9002\u5408\u521b\u5efa\u7d22\u5f15\r\n\r\n# \u2460 \u5728where\u4e2d\uff08\u5305\u62ecGROUP BY\u3001ORDER BY\uff09\u4f7f\u7528\u4e0d\u5230\u7684\u5b57\u6bb5\uff0c\u4e0d\u8981\u8bbe\u7f6e\u7d22\u5f15\r\n\r\n# \u2461 \u6570\u636e\u91cf\u5c0f\u7684\u8868\u6700\u597d\u4e0d\u8981\u4f7f\u7528\u7d22\u5f15\r\n\r\n# \u2462 \u6709\u5927\u91cf\u91cd\u590d\u6570\u636e\u7684\u5217\u4e0a\u4e0d\u8981\u5efa\u7acb\u7d22\u5f15\r\n\r\n# \u7ed3\u8bba\uff1a\u5f53\u6570\u636e\u91cd\u590d\u5ea6\u5927\uff0c\u6bd4\u5982 \u9ad8\u4e8e 10% \u7684\u65f6\u5019\uff0c\u4e5f\u4e0d\u9700\u8981\u5bf9\u8fd9\u4e2a\u5b57\u6bb5\u4f7f\u7528\u7d22\u5f15\u3002\r\n\r\n# \u2463 \u907f\u514d\u5bf9\u7ecf\u5e38\u66f4\u65b0\u7684\u8868\u521b\u5efa\u8fc7\u591a\u7684\u7d22\u5f15\r\n\r\n# \u2464 \u4e0d\u5efa\u8bae\u7528\u65e0\u5e8f\u7684\u503c\u4f5c\u4e3a\u7d22\u5f15\r\n\r\n# \u2465 \u5220\u9664\u4e0d\u518d\u4f7f\u7528\u6216\u8005\u5f88\u5c11\u4f7f\u7528\u7684\u7d22\u5f15\r\n\r\n# \u2466 \u4e0d\u8981\u5b9a\u4e49\u5197\u4f59\u6216\u91cd\u590d\u7684\u7d22\u5f15\r\n\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[47],"class_list":["post-1630","post","type-post","status-publish","format-standard","hentry","category-mysql-code","tag-mysql"],"_links":{"self":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/1630"}],"collection":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1630"}],"version-history":[{"count":1,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/1630\/revisions"}],"predecessor-version":[{"id":1631,"href":"https:\/\/qaqaq.top\/index.php?rest_route=\/wp\/v2\/posts\/1630\/revisions\/1631"}],"wp:attachment":[{"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1630"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1630"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/qaqaq.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1630"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}