1. sql語句（mysql）怎麼去掉欄位內一部分內容
可以使用字元串處理函數來去掉欄位的不分內容，例如insert(),replace()等等函數也可以組合使用它們。
例如下面的例子用這兩個函數分別用零長度字元串將欄位C中第二個字元開始長度為2的字元去掉，以及將欄位C中所有的字元「cd」清除掉：
select c,
insert(c,2,2,''),
replace(c,'cd','') from example;
2. sql 刪除語句
1、delete 語句用於刪除表中的行。delete語句執行刪除的過程是每次從表中刪除一行，並且同時將該行的刪除操作作為事務記錄在日誌中保存
語法：DELETE FROM 表名稱 WHERE 列名稱 = 值，
如：刪除student表中姓名為張三豐的學生信息-delete from studentwhere name=『張三豐』；
2、drop (刪除表)：刪除內容和定義，釋放空間。簡單來說就是把整個表去掉.以後要新增數據是不可能的,除非新增一個表。
drop語句將刪除表的結構被依賴的約束（constrain),觸發器（trigger)索引（index);依賴於該表的存儲過程/函數將被保留，但其狀態會變為：invalid。
3、truncate (清空表中的數據)：刪除內容、釋放空間但不刪除定義(保留表的數據結構)。與drop不同的是,只是清空表數據而已。
注意:truncate 不能刪除行數據,要刪就要把表清空。
(2)sql語句去掉零擴展閱讀：
資料庫操作中，經常要用到刪除表和刪除表數據，在實際應用中，三者的區別是明確的。
當你不再需要該表時， 用 drop;
當你仍要保留該表，但要刪除所有記錄時， 用 truncate;
當你要刪除部分記錄時（always with a WHERE clause), 用 delete。
truncate 與delete 比較：
1、truncate table 在功能上與不帶 WHERE 子句的 delete語句相同：二者均刪除表中的全部行。
2、truncate 比 delete速度快，且使用的系統和事務日誌資源少。
3、truncate 操作後的表比Delete操作後的表要快得多。
3. SQL語句 Decimal如何去掉末尾無用的0
用round函數
select round(A,2) FROM [表名]
round(A,2)中的2表示取小數點後兩位,取3位就寫3,依此類推
4. SQL清除語句
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.
5. sql語句 怎麼去掉小數點後多餘的 0
declare @s numeric(20,10)
set @s = 2555.784000
select
case when cast(@s as float) > cast(cast(@s as float) as INT)
then cast(@s as float)
else cast(cast(@s as float) as int)
end
6. sql語句去掉前面一個零謝謝了，大神幫忙啊
這個欄位是定長的還是不定長的？ 定長的就 select substring(列名,2,3) from table 就行了 不定長的話可以建一個函數做，到時候可以追問
7. sql語句如何去掉沒有值的
你具體想實現什麼功能啊？如果就是篩選記錄的話就是樓上說的那樣。
8. 求sql語句數據里有0001，0010，0101如何只去掉1前邊的0
可以先轉換成int型，再換回varchar就可以
select convert(varchar(4),convert(int,'0001'))
9. 怎麼在sql語句中將月和日中前面的0去掉，比如09月07日，我只有9月7日
selectto_char(to_char(to_date(substr(a.rq,0,10),'yyyy-mm-dd'),'m')||'月'||
to_char(to_date(substr(a.rq,0,10),'yyyy-mm-dd'),'d')||'日')rq
fromJW_PKB_ZTJSa
wherea.jsidin(803,804,805,806,807,808)
groupbya.rq
orderbya.rq
10. sql 中輸入delete語句為什麼提示刪除0行
我想是你的邏輯錯誤。
你把這個觸發器，寫一下。我幫你看一看