经典SQL语句

SQL递归查询数据

Tree表如下:
    NodeId   ParentId     NodeName
    0           -1              &nb ......

Oracle Sql技巧 Upsert, Multitable Insert, Undrop

UpSert功能：
MERGE <hint> INTO <table_name>
USING <table_view_or_query>
ON (<condition>)
WHEN MATCHED THEN <update_clause>
WHEN NOT MATCHED THEN <insert_clause>;
MultiTable Inserts功能：
Multitable inserts allow a single INSERT INTO .. SELECT statement to ......

SQL Server主键自动增长的设置

在SQL Server中，如果把表的主键设为identity类型，数据库就会自动为主键赋值。例如：
create table customers (
id int identity(1,1) primary key not null,
name varchar(15)
);
insert into customers(name) values("name1"),("name2");
select id from customers;

查询结果为：
id
---
1
2
由此� ......

sql 汉字转首字母拼音

create function fun_getPY(@str nvarchar(4000))
returns nvarchar(4000)
as
begin
declare @word nchar(1),@PY nvarchar(4000)
set @PY=''
while len(@str)>0
begin
set @word=left(@str,1)
--如果非汉字字符，返回原字符
set @PY=@PY+(case when unicode(@word) between 19968 and 19968+20901 ......