jz_2017
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JpaRepository Save 慢的问题
- 博客分类：
- Java
检查了代码， 已经写了batch_size。但是还是不管用。
Properties.setProperty("hibernate.jdbc.batch_size", "200");
查询了Stack Overflow， batch_size 不起作用有可能是因为：
Note
Hibernate disables insert batching at the JDBC level transparently if you use an identity identifier generator.
相关链接： ht ...
Below is learnt from my colleague. Next time i wish i can solve it independently.
import static java.util.stream.Collectors.groupingBy;
import static java.util.stream.Collectors.reducing;
import static java.util.stream.Collectors.toList;
import java.util.List;
import java.util.Map;
import ...
https://stackoverflow.com/questions/2095415/oracle-find-a-constraint
java.lang.ArithmeticException:
REM新建文件夹
md [name]
REM 新建文件
echo>[fileName]
REM 删除文件夹
rmdir [name]
REM 判断e:\mybooks\text.txt是否存在，存在显示OK，否则显示err
REM (括号内内容可以换行)
REM @echo off 关掉回显
REM if exist 或者 if not exist
@echo off
if exist "e:\mybooks\text.txt" (echo ok ) else (echo err)
pause
Git Remote branch Merge conflict
situation:
local branch A
remote branch A
master
In local eclipase,
1. [Git Perspective] --> right click branch A --> merge --> choose master.
2. propose the confilict
3. [Team Synchronizing Perspective] --> Mark as Merged --> commit and ...
Identity Insert
- 博客分类：
- MSSQL
identity_insert:
SET IDENTITY_INSERT Entity ON
INSERT INTO Entity (id, name, description) VALUES(1, 'book', 'book')
SET IDENTITY_INSERT Entity OFF
Git Command
- 博客分类：
- Git
REM add all content to index
git add *
REM add all content and commit (-m)
git -am <msg>
REM git push to remote branch
git push origin <branch Name>
Alter Table
- 博客分类：
- MSSQL
add new column to an existed table:
alter table [tblName] add [colName] [type]
* only can add to the tail in MSSQL, in MySQL, can use 'after + [colName]'
delete column:
alter table [tblName]
drop column [colName]
nullif (A, B)
-->return null if A equals B (, else return A)
eg:
select nullif('','') --null
isnull(A, B)
--> if A is null, return B (; else return B)
eg:
select isnull(null,null) --null
select isnull(3,null) --3
select isnull(null,'44') --44
select isnull('33','44') --33
...
Right Click database -> Tasks -> Generate Script.
["Introduction" page: click next]
"Choose Objects" page: click table name(s)
Set Scripting Options: click advanced -> Types of data to script , choose "Schema and data"
click finish