alter table [表名] add column [字段名] [类型]; *删除表中的字段: alter table [表名] drop column [字段名]; *重命名一个字段: alter table [表名] rename column [字段名A] to [字段名B]; *给一个字段设置缺省值: alter table [表名] alter column [字段名] set default [新的默认值]; ...
alter table [表名] alter column [字段名] drop default; *修改表中的某行某列的数据: update [表名] set [目标字段名]=[目标值] where [该行特征]; *删除表中某行数据: delete from [表名] where [该行特征]; delete from [表名]; // 删空整个表 *可以使用pg_dump和pg_dumpall来完成。比如...
--><deleteid="deleteByDynamicConditions"parameterType="map">delete from table_name where 1=1<iftest="column1 != null and column1 != ''">and column1 = #{column1}</if><iftest="column2 != null and column2 != '' ">and column2 = #{column2}</if></delete> 10. 批量删除 批量删...
在PostgreSQL中,可以使用DELETE语句结合子查询来执行基于复杂子查询的内连接删除行操作。DELETE语句用于从表中删除满足指定条件的行。 以下是一个示例的DELETE语句,用于执行基于复杂子查询的内连接删除行操作: 代码语言:txt 复制 DELETE FROM table1 WHERE column1 IN ( SELECT column1 FROM table1 INNER JOIN table2...
SELECT column1, column2,...columnN FROM table_name; 例: select * from postgtest ; 数据抽出选项 order by, limit(只取结果的前几条) , offset (只取从第几条到第几条) 例: select * from postgtest order by title desc limit 3 offset 4 ; 排序后从第4条开始取3条 ...
–`SELECT * FROM tablename;`:从数据表中检索所有行和列 –`UPDATE tablename SET columnname = newvalue WHERE condition;`:更新数据表中符合条件的行的列值 –`DELETE FROM tablename WHERE condition;`:从数据表中删除符合条件的行 3.利用pg_dump和pg_restore进行数据库备份和恢复 ...
copy … from 导入: copy … to 导出(导出weather表全部数据:): Select查询语句 在查询时,可以查询某一张表中的全部字段,或者查询部分字段,或者查询表达式 注:查询表达式,如果没有AS字句,对应字段会用默认命名 ?column?,WHERE条件查询:后面跟bool表达式。查询只返回表达式为true的数据。 多个bool表达式之间用AND(与...
DELETEFROMpublic.student2; 5.6、排序的问题 PostgreSQLORDER BY子句用于按升序或降序对数据进行排序。数据在一列或多列的基础上进行排序。语法:SELECT column-list FROM table_name [WHERE condition] [ORDER BY column1, column2, .. columnN] [ASC | DESC];SQL参数说明:column_list:它指定要检索的列或计算...
Introduction to PostgreSQL DROP COLUMN clause To drop a column of a table, you use the DROP COLUMN clause in the ALTER TABLE statement as follows: ALTER TABLE table_name DROP COLUMN column_name; When you remove a column from a table, PostgreSQL will automatically remove all of the indexes ...
定义一个游标。DECLARE name [ BINARY ] [ INSENSITIVE ] [ [ NO ] SCROLL ] CURSOR [ { WITH | WITHOUT } HOLD ] FOR query [ FOR { READ ONLY | UPDATE [ OF column [, ...] ] } ]DELETE删除一个表中的行。DELETE FROM [ ONLY ] table [ WHERE condition ]...