ALTERTABLEcustomerADDsuburb VARCHAR2(100)DEFAULT'Central'; You can add multiple columns in a single ALTER TABLE command as well. You’ll just need to surround the column details in brackets, and separate them with commas. This is slightly different from other databases which don’t require the...
Learn how to update multiple columns in SQL using a single query for improved efficiency. Explore practical advanced techniques and examples, including single row updates and multiple row updates. Nov 8, 2024 · 8 min read Contents Understanding the Basics of Updating Multiple Columns in SQL Exam...
Add multiple columns to the example_rollup_index (aggregation model) ALTER TABLE example_db.my_table ADD COLUMN (col1 INT DEFAULT "1", col2 FLOAT SUM DEFAULT "2.3") TO example_rollup_index; Delete a column from the example_rollup_index ALTER TABLE example_db.my_table DROP COLUMN col2 F...
mysql> select distinct tiny_column from big_table limit 2; mysql> -- Returns the unique combinations of values from multiple columns. mysql> select distinct tiny_column, int_column from big_table limit 2; distinct可以和聚合函数(通常是count函数)一同使用,count(disitnct)用于计算出一个列或多个...
head_ID is the primary key.\nTable management has columns such as department_ID, head_ID, temporary_acting. department_ID is the primary key.\nThe head_ID of management is the foreign key of head_ID of head.\nThe department_ID of management is the foreign key of Department_ID of ...
error occurs if you try to add a new row with a key value that matches an existing row. If you specify a prefix value for a column in a UNIQUE index, the column values must be unique within the prefix length. A UNIQUE index permits multiple NULL values for columns that can contain ...
hive添加字段:alter table table_name add columns(columns_values bigint comment 'comm_text'); hive修改字段:alter table table_name change old_column new_column string comment 'comm_text'; 删除分区:alter table table_name drop partition(dt='2021-11-30'); ...
SQL_ORDER_BY_COLUMNS_IN_SELECT SQL_OUTER_JOINS SQL_PROCEDURES SQL_QUOTED_IDENTIFIER_CASE SQL_SCHEMA_USAGE SQL_SPECIAL_CHARACTERS SQL_SQL_CONFORMANCE SQL_SUBQUERIES SQL_UNION SQL 限制 InfoType 参数的以下值返回有关应用于 SQL 语句中的标识符和子句的限制的信息,例如标识符的最大长度和选择列表中的最大...
("alter table default_catalog.default_database.t1 add watermark for ts as ts - interval '1' second"); } static void testAlterTableAddMultipleColumn(StreamTableEnvironment tenv) { final String sql1 = "alter table t1 add ( col_int int, log_ts string comment 'log timestamp string' first...
查询表结构 desc score5; 添加列 alter table score5 add columns (mycol string, mysco string); 更新列 alter table score5 change column mysco mysconew int; 删除表操作 drop table score5; 清空表操作 truncate table score6; 说明:只能清空管理表,也就是内部表;清空外部表,会产生错误 注意:truncate...