Welcome to MySQL Workbench:MySQL 字串函式CHAR_LENGTH(pro)
阿新 • • 發佈:2020-11-29
CHAR_LENGTH(pro):
返回字串 pro 的字元數
CREATE TABLE test_NO1( test_NO1_id INT NOT NULL AUTO_INCREMENT, test_NO1_title VARCHAR(100) NOT NULL, test_NO1_author VARCHAR(40) NOT NULL, test_NO1_date DATE, PRIMARY KEY ( test_NO1_id ) )ENGINE=InnoDB; drop table test_no1; INSERT INTO test_NO1 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb", "welcome to programb", NOW()); select * from test_NO1; INSERT INTO test_NO1 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb2", "welcome to programb2", NOW()); INSERT INTO test_NO1 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb3", "welcome to programb3", NOW()); SELECT * from test_NO1 WHERE test_NO1_title='programb2'; SELECT * from test_NO1; update test_NO1 SET test_NO1_title='programb100' WHERE test_NO1_id=1; SELECT * from test_NO1 where test_NO1_id=1; SELECT * from test_NO1; DELETE FROM test_NO1 WHERE test_NO1_id=1; SELECT * from test_NO1; SELECT * from test_NO1 WHERE test_NO1_title LIKE '%programb2'; INSERT INTO test_NO1 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb2", "welcome.to.programb2", NOW()); SELECT * from test_NO1 WHERE test_NO1_author LIKE '%programb2'; SELECT * from test_NO1 WHERE test_NO1_author LIKE '%to%'; SELECT * from test_NO1 WHERE test_NO1_author LIKE 'welcome%'; SELECT * from test_NO1; CREATE TABLE test_NO2( test_NO1_id INT NOT NULL AUTO_INCREMENT, test_NO1_title VARCHAR(100) NOT NULL, test_NO1_author VARCHAR(40) NOT NULL, test_NO1_date DATE, PRIMARY KEY ( test_NO1_id ) )ENGINE=InnoDB; INSERT INTO test_NO2 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb2", "welcome.to.programb2", NOW()); SELECT * from test_NO2; SELECT test_NO1_author FROM test_no1 UNION SELECT test_NO1_author FROM test_no2 ORDER BY test_NO1_author; SELECT test_NO1_author FROM test_no1 UNION all SELECT test_NO1_author FROM test_no2 ORDER BY test_NO1_author; select * from test_no1 order by test_NO1_date asc; INSERT INTO test_NO1 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb4", "welcome to programb4", NOW()); INSERT INTO test_NO1 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb5", "welcome to programb5", NOW()); select * from test_no1 order by test_NO1_date asc; select * from test_no1 order by test_NO1_date desc; select test_NO1_title, count(*) from test_no1 group by test_NO1_title; select test_NO1_title, sum(test_NO1_id) from test_no1 group by test_NO1_title; select test_NO1_title, avg(test_NO1_id) from test_no1 group by test_NO1_title; SELECT * from test_NO1; SELECT * from test_no2; INSERT INTO test_NO2 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb4", "welcome to programb4", NOW()); INSERT INTO test_NO2 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb2", "welcome to programb2", NOW()); SELECT * from test_no2; select t1.test_NO1_title, t2.test_NO1_date from test_no1 t1, test_no2 t2 where t1.test_NO1_date=t2.test_NO1_date; select t1.test_NO1_title, t2.test_NO1_date from test_no1 t1 left join test_no2 t2 on t1.test_NO1_date=t2.test_NO1_date; select t1.test_NO1_title, t2.test_NO1_date from test_no1 t1 right join test_no2 t2 on t1.test_NO1_date=t2.test_NO1_date; SELECT * from test_no2; INSERT INTO test_NO2 (test_NO1_title, test_NO1_author, test_NO1_date ) VALUES ("programb2", "welcome", NOW()); SELECT * from test_no2; select * from test_no2 where test_NO1_author is null; INSERT INTO test_NO2 (test_NO1_title, test_NO1_author ) VALUES ("programb2", "welcome"); INSERT INTO test_NO2 (test_NO1_title, test_NO1_author ) VALUES ("programb2", "welcome"); INSERT INTO test_NO2 (test_NO1_title, test_NO1_author ) VALUES ("programb2", "welcome"); SELECT * from test_no2; select * from test_no2 where test_NO1_date is null; select * from test_no2 where test_NO1_date is not null; select * from test_no1 where test_NO1_title regexp '^pro'; select * from test_no1 where test_NO1_title regexp '2$'; select * from test_no1 where test_NO1_title regexp 'gra'; select * from test_no1 where test_NO1_title regexp '^[pro]|5$'; begin; insert into test_NO1(test_NO1_title, test_NO1_author ) value("pro","welcome"); insert into test_NO1(test_NO1_title, test_NO1_author ) value("pro","welcome"); insert into test_NO1(test_NO1_title, test_NO1_author ) value("pro","welcome"); insert into test_NO1(test_NO1_title, test_NO1_author ) value("pro","welcome"); insert into test_NO1(test_NO1_title, test_NO1_author ) value("pro","welcome"); insert into test_NO1(test_NO1_title, test_NO1_author ) value("pro","welcome"); commit; SELECT * from test_NO1; show columns from test_no1; alter table test_no1 alter test_NO1_author set default 1000; alter table test_no1 modify test_NO1_author varchar(100); show columns from test_no1; alter table test_no1 drop test_NO1_author; show columns from test_no1; alter table test_no1 add test_NO1_author int first; show columns from test_no1; alter table test_no1 drop test_NO1_author; alter table test_no1 add test_NO1_author int; show columns from test_no1; alter table test_no1 drop test_NO1_author; alter table test_no1 add test_NO1_author varchar(100); CREATE TABLE test_no3(ID INT NOT NULL,username VARCHAR(16) NOT NULL, INDEX username2 (username(12))); show columns from test_no3; SELECT * from test_no3; select username from test_no3; SHOW INDEX FROM test_no3; DROP INDEX username2 ON test_no3; SHOW INDEX FROM test_no3; ALTER TABLE test_no3 ADD INDEX (username); ALTER TABLE test_no3 DROP INDEX username; CREATE TEMPORARY TABLE test_no4 (test_name VARCHAR(50) NOT NULL); select * from test_no4; DROP TABLE test_no4; INSERT INTO test_no4 (test_name)VALUES(1000000); select * from test_no3; SHOW CREATE TABLE test_no3; INSERT INTO test_no3 (id,username)VALUES(1,1000000); select * from test_no3; CREATE TABLE test_no5 (id int ,username VARCHAR(50) NOT NULL); INSERT INTO test_no5(id,username)SELECT id,username FROM test_no3; select * from test_no5; SELECT VERSION(); SELECT USER(); SELECT DATABASE(); SHOW STATUS; SHOW VARIABLES; CREATE TABLE test_no6(id INT UNSIGNED NOT NULL AUTO_INCREMENT,PRIMARY KEY (id),name VARCHAR(30) NOT NULL); INSERT INTO test_no6 (id,name)values(null,'1001'); INSERT INTO test_no6 (id,name)values(null,'1002'); INSERT INTO test_no6 (id,name)values(null,'1003'); INSERT INTO test_no6 (id,name)values(null,'1004'); INSERT INTO test_no6 (id,name)values(null,'1005'); INSERT INTO test_no6 (id,name)values(null,'1006'); INSERT INTO test_no6 (id,name)values(null,'1007'); SELECT * FROM test_no6 ORDER BY id; CREATE TABLE test_no7(first_name CHAR(20),last_name CHAR(20),sex CHAR(10)); CREATE TABLE test_no8(first_name CHAR(20) NOT NULL,last_name CHAR(20) NOT NULL,sex CHAR(10),PRIMARY KEY (last_name, first_name)); CREATE TABLE test_no9(first_name CHAR(20) NOT NULL,last_name CHAR(20) NOT NULL,sex CHAR(10),UNIQUE (last_name, first_name)); SELECT * FROM test_no1 INTO OUTFILE 'f:\ddd.txt'; SELECT ASCII(test_NO1_title) AS test_NO1_title FROM test_no1; select * from test_no1; SELECT CHAR_LENGTH("test_NO1_title") AS test_NO1_title;
SELECT CHAR_LENGTH("test_NO1_title") AS test_NO1_title;