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countÓï¾äÖ§³Ö*¡¢ÁÐÃû¡¢³£Á¿¡¢±äÁ¿,²¢ÇÒ¿ÉÒÔÓÃdistinct¹Ø¼ü×ÖÐÞÊΣ¬ ²¢ÇÒcount(ÁÐÃû)²»»áÀÛ¼ÆnullµÄ¼Ç¼¡£ÏÂÃæËæ±ãÓÃһЩÀý×Óʾ·¶Ò»ÏÂcountµÄ¹æÔò£º±ÈÈç¶ÔÈçϱí×öͳ¼Æ£¬ËùÓÐÁÐÕâÀï¶¼ÓÃsql_variantÀàÐÍÀ´±íʾ¡£
if (object_id ('t_test' )> 0 )
    drop table t_test
go
create table t_test (a sql_variant , b sql_variant , c sql_variant )
insert into t_test select 1 , 1 , 'a'
insert into t_test select 1 , getdate (), null
insert into t_test select 'a' , null , 1
insert into t_test select 3 , null , null
insert into t_test select null , null , null
go
select * from t_test
go
select
     count (* )                --×ÜÊý
    , count (nullif (1 , 1 ))        --ÓÀÔ¶·µ»Ø0
    , count (a )                --aÊýÁ¿
    , count (b)                --bÊýÁ¿
    , count (distinct a )        --a²»Öظ´ÊýÁ¿
    , count (isnull (b, c ))        --b»òÕßc²»ÎªnullÊýÁ¿
    , count (Coalesce (a , b, c ))    --a»òÕßb»òÕßc²»ÎªnullÊýÁ¿
    , count (nullif (a , b))        --a²»µÈÓÚbµÄÊýÁ¿
    , count (nullif (isnumeric (cast (a as varchar (38 ))), 0 ))--aÊÇÊý×ÖµÄÊýÁ¿
from t_test


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DDL—Êý¾Ý¶¨ÒåÓïÑÔ(CREATE£¬ALTER£¬DROP£¬DECLARE)
DML—Êý¾Ý²Ù×ÝÓïÑÔ(SELECT£¬DELETE£¬UPDATE£¬INSERT)
DCL—Êý¾Ý¿ØÖÆÓïÑÔ(GRANT£¬REVOKE£¬COMMIT£¬ROLLBACK)
Ê×ÏÈ,¼òÒª½éÉÜ»ù´¡Óï¾ä:
1¡¢ËµÃ÷£º´´½¨Êý¾Ý¿â
CREATE DATABASE database-nam ......

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SQL> select count(*) from v$session  #Á¬½ÓÊý
SQL> Select count(*) from v$session where status='ACTIVE'¡¡#²¢·¢Á¬½ÓÊý
SQL> show parameter processes  #×î´óÁ¬½Ó
SQL> alter system set processes = value scope = spfile;ÖØÆôÊý¾Ý¿â  #ÐÞ¸ÄÁ¬½Ó ......

MS SQL Server2000 ÔÚtomcatϵÄÊý¾ÝÔ´ÅäÖÃ

MS SQL Server2000 Êý¾ÝÔ´ÅäÖÃ
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<?xml version="1.0" encoding="UTF-8"?>
<Context>
    <Resource name="jdbc/sqlserver"
   &nbs ......

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