A
a_id a_title a_key a_desc a_pid
1 A A A 1
B
b_id b_title b_key b_desc b_pid
1 b 2
C
c_id c_title c_key c_desc c_pid
1
$title= Ctitile || Btitile || Atitile
C,B,BA
union . As for determining which table title is empty, leave it to programming language to do
SELECT IFNULL(c.c_title, IFNULL(b.b_title, a.a_title)) FROM c
LEFT JOIN b ON b.b_id = c.c_id
LEFT JOIN a ON a.a_id = c.c_id
LIMIT 1Previous: Valet installation cannot connect to php
Next: Call the API to get permanent material list with Wechat test number for 45009 in a few times.
how to realize the if judgment of mysql. There is now a table with two key fields SELECT * FROM house WHERE price= 8500 OR shoufu= 30 I think, when the $price passed in by php is empty, the sql search statement is SELECT * FROM house WHERE s...
Table 1 fields are as follows 2 3 1event_description_description_id2id1cel_order_item_order_item_id3id 123idnull id ask the boss for advice ...
I have found many articles on utf8_unicode_ci, utf8_general_ci and utf8_bin collation on the Internet, and I generally know that ci is case ignore, etc., but I didn t mention what other collations mean . what does the utf8mb4_polish_ci collation her...
how to design a database of classified information? I want to write all the main contents of the information (title,content) in an info table. I don t know how to design the table for special properties. category table-Real Estate Job Category in...
The database has a doneNum field that represents the number of completions. It was originally designed as varchar (38) with this schedule in mind. doneNum sum(doneNum) I would like to ask you, is there any other solution? ...
id name relation 1 n1 r1 2 n2 r2 3 n4 r1 4 n5 r1 5 n6 r2 6 n6 r1 the relation relationship of the table is shown above where the relation field indicates the relationship between the cur...
mysql imports a csv,csv format that is the character set of the utf8, table and utf8,. After importing, everything in select from an on the terminal is empty, but on phpmyadmin using select from a, there is data. If select * from a where name = xx ,...
now I can only set apache, to restart every hour in cron, but this method treats the symptoms rather than the root of the problem. I am Ubuntu 16 + apache2 + php7.0 + mysql5.7 after running for a period of time, mysql hung up, and restart prompted in...