sql alert 修改表或增加列

ALTER TABLE table_name  ADD column_name datatype

来看个增加例的实例:

<pre class="brush:php;toolbar:false">ALTER TABLE tname  ALTER COLUMN data year

这样给tname表加上了一个列为data 类型的year字段

上面是在表中加列的语法下面我们再来看看删除列吧 DROP COLUMN column_name

ALTER TABLE table_name DROP COLUMN column_name

来看个<strong>删除列</strong>实例.

<pre class="brush:php;toolbar:false">ALTER TABLE Persons DROP COLUMN DateOfBirth

再来修改字段类型:

 ALTER COLUMN column_name datatype _id order by w_support desc

P_Id  LastName   FirstName  Address City <br>1       Hansen      Ola        Timoteivn 10 Sandnes <br>2       Svendson    Tove       Borgvn 23 Sandnes <br>3      Pettersen     Kari      Storgt 20 Stavanger

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