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有关详细信息,请参阅FROM (Transact-SQL)。 WHERE 指定用于限制删除行数的条件。 如果没有提供 WHERE 子句,则 DELETE 删除表中的所有行。 基于WHERE 子句中所指定的条件,有两种形式的删除操作: 搜索删除指定搜索条件以限定要删除的行。 例如,WHEREcolumn_name=value。
5 Coffee Table 180 Living 6 Small Bin 40 Bathroom You don’t always have to delete based on a column equalling a text value. Other DELETE statements we could have run, which will delete different rows, could have included different WHERE clauses: WHERE price = 80; WHERE price > 100; WH...
ALTERTABLEtbl_nameADDCOLUMNcol_name col_type,ALGORITHM=INPLACE,LOCK=NONE; ALGORITHM选项 INPLACE:替换:直接在原表上面执行DDL的操作。 COPY:复制:使用一种临时表的方式,克隆出一个临时表,在临时表上执行DDL,然后再把数据导入到临时表中,在重命名等。这期间需要多出一倍的磁盘空间来支撑这样的 操作。执行期间...
from table_name [where ...] [order by ...] limit s, n; 从s 开始,筛选 n 条结果,比第二种用法更明确 select ... from table_name [where ...] [order by ...] limit n offset s; 对未知表进行查询时,最好加一条 limit 1,避免因为表中数据过大,查询全表数据导致数据库卡死。
[ ,...n ]ON<join_condition>[WHERE<search_condition>] [OPTION(<query_options>[ ,...n ] ) ] [; ]<join_table_source>::={ [database_name. [schema_name] . |schema_name. ]table_or_view_name[AS]table_or_view_alias[<tablesample_clause>] |derived_table[AS]table_alias[ (column_...
[ ,...n ]ON<join_condition>[WHERE<search_condition>] [OPTION(<query_options>[ ,...n ] ) ] [; ]<join_table_source>::={ [database_name. [schema_name] . |schema_name. ]table_or_view_name[AS]table_or_view_alias[<tablesample_clause>] |derived_table[AS]table_alias[ (column_...
[ ,...n ]ON<join_condition>[WHERE<search_condition>] [OPTION(<query_options>[ ,...n ] ) ] [; ]<join_table_source>::={ [database_name. [schema_name] . |schema_name. ]table_or_view_name[AS]table_or_view_alias[<tablesample_clause>] |derived_table[AS]table_alias[ (column_...
DELETEFROMtarget_tableWHEREtarget_table.columnIN(SELECTjoin_table.columnFROMjoin_tableWHEREjoin_table.condition ); target_table:需要删除数据的目标表。 join_table:用于连接的表,提供删除条件。 column:连接条件中的列。 condition:连接条件中的其他条件。
varchar(2));在表emp中删除一个字段 sexyalter table emp drop column sexy;删除多个字段alter table ...