大约有 41,000 项符合查询结果（耗时：0.0371秒） [XML]
Count the number of occurrences of a string in a VARCHAR field?
...
This should do the trick:
SELECT
title,
description,
ROUND (
(
LENGTH(description)
- LENGTH( REPLACE ( description, "value", "") )
) / LENGTH("value")
) AS count
FROM <tab...
How to trim a string in SQL Server before 2017?
...
SELECT LTRIM(RTRIM(Names)) AS Names FROM Customer
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Group query results by month and year in postgresql
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select to_char(date,'Mon') as mon,
extract(year from date) as yyyy,
sum("Sales") as "Sales"
from yourtable
group by 1,2
At the request of Radu, I will explain that query:
to_char(date,'Mon') as mon, : convert...
How to calculate age (in years) based on Date of Birth and getDate()
...low:
try this:
DECLARE @dob datetime
SET @dob='1992-01-09 00:00:00'
SELECT DATEDIFF(hour,@dob,GETDATE())/8766.0 AS AgeYearsDecimal
,CONVERT(int,ROUND(DATEDIFF(hour,@dob,GETDATE())/8766.0,0)) AS AgeYearsIntRound
,DATEDIFF(hour,@dob,GETDATE())/8766 AS AgeYearsIntTrunc
OUTPUT:
Age...
Best way to check for “empty or null value”
... '
Demo
Empty string equals any string of spaces when cast to char(n):
SELECT ''::char(5) = ''::char(5) AS eq1
, ''::char(5) = ' '::char(5) AS eq2
, ''::char(5) = ' '::char(5) AS eq3;
Result:
eq1 | eq2 | eq3
----+-----+----
t | t | t
Test for "null or empty string" w...
PostgreSQL: Difference between text and varchar (character varying)
... article does detailed testing to show that the performance of inserts and selects for all 4 data types are similar. It also takes a detailed look at alternate ways on constraining the length when needed. Function based constraints or domains provide the advantage of instant increase of the length c...
Replace a newline in TSQL
...e any of CR, LF or CR+LF. To get them all, you need something like this:
SELECT REPLACE(REPLACE(@str, CHAR(13), ''), CHAR(10), '')
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Generate class from database table
...eName'
declare @Result varchar(max) = 'public class ' + @TableName + '
{'
select @Result = @Result + '
public ' + ColumnType + NullableSign + ' ' + ColumnName + ' { get; set; }
'
from
(
select
replace(col.name, ' ', '_') ColumnName,
column_id ColumnId,
case typ.name...
byte[] to hex string [duplicate]
...);
}
static string LinqConcat(byte[] data)
{
return string.Concat(data.Select(b => b.ToString("X2")).ToArray());
}
static string LinqJoin(byte[] data)
{
return string.Join("",
data.Select(
bin => bin.ToString("X2")
).ToArray());
}
static string LinqAgg(b...
C++实现一款简单完整的聊天室服务器+客户端 - C/C++ - 清泛网 - 专注C/C++及内核技术
C++实现一款简单完整的聊天室服务器+客户端Linux下select函数实现的聊天服务器消息缓冲区类MessageBuffer，接收线程将受到的消息放入缓冲区，发送线程从缓冲区中取出消息MessageBuffe...目录：
Linux下select函数实现的聊天服务器
基...