大约有 37,000 项符合查询结果（耗时：0.0206秒） [XML]
Multiple Updates in MySQL
... use INSERT ... ON DUPLICATE KEY UPDATE.
Using your example:
INSERT INTO table (id,Col1,Col2) VALUES (1,1,1),(2,2,3),(3,9,3),(4,10,12)
ON DUPLICATE KEY UPDATE Col1=VALUES(Col1),Col2=VALUES(Col2);
share
|
...
Throw an error in a MySQL trigger
If I have a trigger before the update on a table, how can I throw an error that prevents the update on that table?
7 An...
SET versus SELECT when assigning variables?
... @var varchar(20)
set @var = 'Joe'
set @var = (select name from master.sys.tables where name = 'qwerty')
select @var /* @var is now NULL */
set @var = 'Joe'
select @var = name from master.sys.tables where name = 'qwerty'
select @var /* @var is still equal to 'Joe' */
...
Generate GUID in MySQL for existing Data?
I've just imported a bunch of data to a MySQL table and I have a column "GUID" that I want to basically fill down all existing rows with new and unique random GUID's.
...
In MySQL, can I copy one row to insert into the same table?
I just want to copy one row to insert into the same table (i.e., I want to duplicate an existing row in the table) but I want to do this without having to list all the columns after the "select", because this table has too many columns.
...
EF Code First “Invalid column name 'Discriminator'” but no inheritance
I have a table in my database called SEntries (see below the CREATE TABLE statement). It has a primary key, a couple of foreign keys and nothing special about it. I have many tables in my database similar to that one, but for some reason, this table ended up with a "Discriminator" column on the EF P...
Vertically align text next to an image?
...lt;/div>
Multiple-lines vertical-align:middle
<div style="display:table;width:30px;height:60px;">
<div style="display:table-cell;height:30px;">This is positioned in the middle</div>
</div>
If you must support ancient versions of IE <= 7
In order to get this to w...
Why should hash functions use a prime number modulus?
A long time ago, I bought a data structures book off the bargain table for $1.25. In it, the explanation for a hashing function said that it should ultimately mod by a prime number because of "the nature of math".
...
How to remove a column from an existing table?
How to remove a column from an existing table?
11 Answers
11
...
For loop example in MySQL
...
drop table if exists foo;
create table foo
(
id int unsigned not null auto_increment primary key,
val smallint unsigned not null default 0
)
engine=innodb;
drop procedure if exists load_foo_test_data;
delimiter #
create procedur...