ADD COLUMN new_column_name column_data_type; 在上面的命令中,将your_table_name替换为你要添加字段的表的名称,将new_column_name替换为新字段的名称,将column_data_type替换为新字段的数据类型。 如果新字段需要设置默认值,可以使用DEFAULT关键字: ALTER TABLE your_t
ADD color VARCHAR(255); Result ALTER TABLE Display Table To check the result we can display the table with this SQL statement: Example SELECT * FROM cars; Run Example » As you can see, thecarstable now has acolorcolumn. The new column is empty, you will learn how to fill it with ...
Summary: in this tutorial, you will learn how to use the PostgreSQL ADD COLUMN statement to add one or more columns to an existing table. Introduction to the PostgreSQL ADD COLUMN statement To add a new column to an existing table, you use the ALTER TABLE ADD COLUMN statement as follows:...
it was virtually instantaneous. Get a lock on table, add information about new column to system catalogs, and it's done. But when you tried: ALTERTABLE xADDCOLUMN z textDEFAULT'some value'; then it took long time. How long it did depend on size of table. This was because postgresql w...
数据集成对ADD COLUMN进行了特别支持: 约束:ADD COLUMN时不能有ADD COLUMN和DROP COLUMN或者其他DDL的组合。 重要 ADD COLUMN时其他DROP COLUMN、RENAME COLUMN等ALTER COLUMN的行为将使数据同步任务不能正常工作。 限制:除了ADD COLUMN外,无法识别用户的其他DDL操作。
RENAME TO new_name ALTER TABLE name SET SCHEMA new_schema 这里action 是下列之一: ADD [ COLUMN ] column type [ column_constraint [ ... ] ] DROP [ COLUMN ] column [ RESTRICT | CASCADE ] ALTER [ COLUMN ] column TYPE type [ USING expression ] ...
alter命令原表就不支持给索引重命名,需要先drop再add,在pt-osc也一样。 但给字段重命名,千万不要drop-add,整列数据会丢失,使用change col1 col1_new type constraint(保持类型和约束一致,否则相当于修改 column type,不能online) 子句如果是add column并且定义了not null,那么必须指定default值,否则会失败。
CREATETABLEtable_name(...){PARTITIONBY{RANGE|LIST}({column_name|(expression)} 创建主表时须指定分区方式,可选的分区方式为RANGE范围分区或LIST列表分区,并指定字段或表达式作为分区键。 创建分区的语法如下: 代码语言:javascript 代码运行次数:0 运行 ...
bigtableaddcolumnnew_idbigint;createuniqueindexconcurrentlyonbigtable (new_id);createuniqueindexconcurrentlyonchild1 (new_id);createuniqueindexconcurrentlyonchild2 (new_id);createor replacefunctionid_handler()returnstriggeras$$beginnew.new_id =new.id;-- id 是int4类型 , newid是int8类型returnnew;end...
table_name ADD COLUMN col3 string DEFAULT ''; 六、pg删除字段默认值 代码语言:javascript 代码运行次数:0 运行 AI代码解释 ALTER TABLE public.table_name ALTER COLUMN col3 DROP DEFAULT; 七、pg新增字段 代码语言:javascript 代码运行次数:0 运行 AI代码解释 ALTER TABLE public.table_name ADD column col...