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MySQL复制的概述、安装、故障、技巧、工具 - 数据库(内核) - 清泛网 - 专注...
...--master-data=1 > data.sql
注：master-data选项缺省会打开lock-all-tables，并写入CHANGE MASTER TO语句。
如果数据库使用的是InnoDB表类型的话，则应该使用single-transcation：
shell> mysqldump --all-databases --single-transaction --master-data=1 > data.sql
有了...
Big O, how do you calculate/approximate it?
...(1) - Determining if a number is even or odd; using a constant-size lookup table or hash table
O(logn) - Finding an item in a sorted array with a binary search
O(n) - Finding an item in an unsorted list; adding two n-digit numbers
O(n2) - Multiplying two n-digit numbers by a simple algorithm; add...
What does “static” mean in C?
...If we compile:
int i = 0;
static int si = 0;
and disassemble the symbol table with:
readelf -s main.o
the output contains:
Num: Value Size Type Bind Vis Ndx Name
5: 0000000000000004 4 OBJECT LOCAL DEFAULT 4 si
10: 0000000000000000 4 OBJECT GLOBAL DEFAULT...
Why doesn't Objective-C support private methods?
... were private; i.e. this could be achieved by adding a private-only method table to the Class structure.
There would be no way for a private
method to short-circuit this check or
skip the runtime?
It couldn't skip the runtime, but the runtime wouldn't necessarily have to do any...
How do I horizontally center a span element inside a div
...
another option would be to give the span display:table; and center it via margin:0 auto;
span {
display:table;
margin:0 auto;
}
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Query for array elements inside JSON type
... json type in PostgreSQL 9.3.
I have a json column called data in a table called reports . The JSON looks something like this:
...
Best data type for storing currency values in a MySQL database
...
My benefit was this.. I needed all my table rows to equal a particular amount of money. Let's say that amount is $10.00. As new rows get added each row amount changes. If there are 3 rows in the table. 10 / 3 = 3.3333333333... but with only 2 decimals they are st...
SQL Server 2012 column identity increment jumping from 6 to 1000+ on 7th entry [duplicate]
...ork for hosted Sql Server Express installations. So, I created an identity table, and use this through an INSTEAD OF trigger. I'm hoping this helps someone else, and/or gives others an opportunity to improve my solution. The last line allows returning the last identity column added. Since I typicall...
How to check if a database exists in SQL Server?
...ing the INFORMATION_SCHEMA views rather than directly accessing the system tables.
– mwigdahl
Mar 24 '09 at 20:09
4
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What is the difference between tinyint, smallint, mediumint, bigint and int in MySQL?
... take up different amounts of space and they have different ranges of acceptable values.
Here are the sizes and ranges of values for SQL Server, other RDBMSes have similar documentation:
MySQL
Postgres
Oracle (they just have a NUMBER datatype really)
DB2
Turns out they all use the same specific...