⑴ 删除一个表的sql 语句怎么写啊
使用drop语句，droptable （需要删除表的名字）。
drop是删除整个表，delete是删除表的内容。
drop语句的作用：删除内容和定义，释放空间，简单来说就是把整个表去掉。以后要新增数据是不可能的，除非新增一个表。
删除表时需要注意的事项：
1、如果删除应用表别名，则delete 后面一定要接对应的别名，然后再接表名，不然报错。
2、delete删除sql后面不可接通配符*，即delete * from ，这样会报错。
3、delete删除sql默认的返回值为int数据类型，当删除一条数据时，返回int数据1，当删除num条数据时，则返回int类型num。
(1)删除sql语句扩展阅读：
SQL即结构化查询语言(Structured Query Language)，是一种特殊目的的编程语言，是一种数据库查询和程序设计语言，用于存取数据以及查询、更新和管理关系数据库系统；同时也是数据库脚本文件的扩展名。
SQL语句无论是种类还是数量都是繁多的，很多语句也是经常要用到的，SQL查询语句就是一个典型的例子，无论是高级查询还是低级查询，SQL查询语句的需求是最频繁的。
常用语句：
创建数据库 CREATE DATABASE database-name
删除数据库 drop database dbname
创建新表 create table tabname(col1 type1 [not null] [primary key],col2 type2 [not null],..)
删除新表 drop table tabname
参考资料：网络—sql语句大全
⑵ mysql 删除sql语句
只能先删外表，后删主表
delete
from
s_text
where
pid=5;
delete
from
test
where
id=5;
分步执行吧
数据库就是怕这样乱删，会导致错误才弄的外键，所以麻烦点就麻烦点吧
⑶ SQL语句如何删除列
方法和详细的操作步骤如下：
1、第一步，打开数据库管理平台软件[SQL Server Management Studio]，见下图，转到下面的步骤。
⑷ SQL删除语句
首先将shee1和persinfo2个表合并到一起，这里用视图来实现：
create view A as
（
select sheet1.用户id ，sheet1.名称，sheet1.日期，persinfo.cardid ，persinfo.phycardid from sheet1 ， persinfo
where sheet1.用户id=persifo.用户id
）
利用视图删除
delete from basedata ， A where A.phycardid =basedata.chrphycardid and Convert(varchar(10),a.日期,120)=Convert(varchar(10),basedatadatadate,120)
⑸ 关于删除的sql语句如何做
对，一般最好把SQL语句写在一个STRING里，要养成好习惯。
⑹ SQL清除语句
CREATE SNAPSHOT [schema.]snapshot
[ [PCTFREE integer] [PCTUSED integer]
[INITRANS integer] [MAXTRANS integer]
[TABLESPACE tablespace]
[STORAGE storage_clause]
[ USING INDEX [ PCTFREE integer | TABLESPACE tablespace
| INITTRANS integer | MAXTRANS integer
| STORAGE storage_clause ] ...
| [CLUSTER cluster (column [, column]...)] ]
[ REFRESH [FAST | COMPLETE | FORCE] [START WITH date] [NEXT date]]
AS subquery
schema
is the schema to contain the snapshot. If you omit schema, Oracle
creates the snapshot in your schema.
snapshot
is the name of the snapshot to be created.
Oracle chooses names for the table, views, and index used to
maintain the snapshot by prefixing the snapshot name. To limit
these names to 30 bytes and allow them to contain the entire
snapshot name, Oracle Corporation recommends that you limit your
snapshot names to 23 bytes.
PCTFREE
PCTUSED
INITRANS
MAXTRANS
establishes values for these parameters for the internal table
Oracle uses to maintain the snapshot's data.
TABLESPACE
specifies the tablespace in which the snapshot is to be created. If
you omit this option, Oracle creates the snapshot in the default
tablespace of the owner of the snapshot's schema.
STORAGE
establishes storage characteristics for the table Oracle uses to
maintain the snapshot's data.
USING INDEX
specifies the storage characteristics for the index on a simple
snapshot. If the USING INDEX clause not specified, the index is
create with the same tablespace and storage parameters as the
snapshot.
CLUSTER
creates the snapshot as part of the specified cluster. Since a
clustered snapshot uses the cluster's space allocation, do not use
the PCTFREE, PCTUSED, INITRANS, or MAXTRANS parameters, the
TABLESPACE option, or the STORAGE clause in conjunction with the
CLUSTER option.
REFRESH
specifies how and when Oracle automatically refreshes the snapshot:
FAST
specifies a fast refresh, or a refresh using only the
updated data stored in the snapshot log associated
with the master table.
COMPLETE
specifies a complete refresh, or a refresh that re-
executes the snapshot's query.
FORCE
specifies a fast refresh if one is possible or
complete refresh if a fast refresh is not possible.
Oracle decides whether a fast refresh is possible at
refresh time.
If you omit the FAST, COMPLETE, and FORCE options,
Oracle uses FORCE by default.
START WITH
specifies a date expression for the first automatic
refresh time.
NEXT
specifies a date expression for calculating the
interval between automatic refreshes.
Both the START WITH and NEXT values must evaluate to a time in the
future. If you omit the START WITH value, Oracle determines the
first automatic refresh time by evaluating the NEXT expression when
you create the snapshot. If you specify a START WITH value but omit
the NEXT value, Oracle refreshes the snapshot only once. If you
omit both the START WITH and NEXT values or if you omit the REFRESH
clause entirely, Oracle does not automatically refresh the snapshot.
AS subquery
specifies the snapshot query. When you create the snapshot, Oracle
executes this query and places the results in the snapshot. The
select list can contain up to 253 expressions. A snapshot query is
subject to the same restrictions as a view query.
PREREQUISITES:
To create a snapshot in your own schema, you must have CREATE
SNAPSHOT system privilege. To create a snapshot in another user's
schema, you must have CREATE ANY SNAPSHOT system privilege.
Before a snapshot can be created, the user SYS must run the SQL
script DBMSSNAP.SQL on both the database to contain the snapshot and
the database(s) containing the tables and views of the snapshot's
query. This script creates the package SNAPSHOT which contains both
public and private stored proceres used for refreshing the
snapshot and purging the snapshot log. The exact name and location
of this script may vary depending on your operating system.
When you create a snapshot, Oracle creates a table, two views, and
an index in the schema of the snapshot. Oracle uses these objects
to maintain the snapshot's data. You must have the privileges
necessary to create these objects. For information on these
privileges, see the CREATE TABLE, CREATE VIEW, and CREATE INDEX
commands.
The owner of the schema containing the snapshot must have either
space quota on the tablespace to contain the snapshot or UNLIMITED
TABLESPACE system privilege. Also, both you (the creator) and the
owner must also have the privileges necessary to issue the
snapshot's query.
To create a snapshot, you must be using Oracle with the proceral
option. To create a snapshot on a remote table or view, you must
also be using the distributed option.
⑺ sql删除语句
delete后面最多允许一个字段,而且出现一个字段的情况是表里面只有一个字段.
所以这个语句没有
⑻ sql语句删除数据
如果是 <NULL> 用update
删除是删除单条或多条记录不是修改值，楼主视乎还不是很理解sql语句的用法
⑼ 删除数据库的sql语句如何写
1、drop database：数据库名--删除数据库的。
2、drop table：表名--删除表的。
3、delete from：表名--where条件--删除数据的。
4、truncate table：表名--也是删除数据库的。
拓展资料
1、SQL即结构化查询语言(Structured Query Language)，是一种特殊目的的编程语言，是一种数据库查询和程序设计语言，用于存取数据以及查询、更新和管理关系数据库系统；同时也是数据库脚本文件的扩展名。
2、SQL语句无论是种类还是数量都是繁多的，很多语句也是经常要用到的，SQL查询语句就是一个典型的例子，无论是高级查询还是低级查询，SQL查询语句的需求是最频繁的。
⑽ SQL删除语句（有条件的）
delete from URTAB where id not in (select parentid from URTAB)
这样会把所有末梢部门全部宰了，这里末梢部门指所有没有子部门的单位——
不管它有没有父部门
如果需要保留没有父部门的，加上一个条件
delete from URTAB where parentid not null and id no in (select parentid from URTAB)