大约有 37,000 项符合查询结果（耗时：0.0478秒） [XML]
PostgreSQL wildcard LIKE for any of a list of words
...t's say that list is ['foo', 'bar', 'baz'] . I want to find any row in my table that has any of those words. This will work, but I'd like something more elegant.
...
'Incomplete final line' warning when trying to read a .csv file into R
...here's no way that in your case the warning was thrown by the function readTableHeader, because that one doesn't read the final line. Hence your problem is not the same as that of the OP.
– Joris Meys
May 1 at 11:31
...
Oracle “(+)” Operator
..., because the ANSI-89 format (using a comma in the FROM clause to separate table references) didn't standardize OUTER joins.
The query would be re-written in ANSI-92 syntax as:
SELECT ...
FROM a
LEFT JOIN b ON b.id = a.id
This link is pretty good at explaining the difference between JOIN...
MySQL: determine which database is selected?
...
DUAL is an Oracle table, that was taken over into MySQL. It's a dummy table for operations that do not require an actual table. en.wikipedia.org/wiki/DUAL_table
– Jan Thomä
Nov 11 '11 at 16:03
...
How to include “zero” / “0” results in COUNT aggregate?
...u want an outer join for this (and you need to use person as the "driving" table)
SELECT person.person_id, COUNT(appointment.person_id) AS "number_of_appointments"
FROM person
LEFT JOIN appointment ON person.person_id = appointment.person_id
GROUP BY person.person_id;
The reason why this is wo...
What's the best practice for primary keys in tables?
When designing tables, I've developed a habit of having one column that is unique and that I make the primary key. This is achieved in three ways depending on requirements:
...
How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...ions:
Individual insert/update operations in a retry loop; or
Locking the table and doing batch merge
Individual row retry loop
Using individual row upserts in a retry loop is the reasonable option if you want many connections concurrently trying to perform inserts.
The PostgreSQL documentation co...
How do I flush the PRINT buffer in TSQL?
... on PRINT or RAISERROR and just load your "print" statements into a ##Temp table in TempDB or a permanent table in your database which will give you visibility to the data immediately via a SELECT statement from another window. This works the best for me. Using a permanent table then also serves a...
PHP + MySQL transactions examples
...b_passwd,$db_name); // error-check this
// note: this is meant for InnoDB tables. won't work with MyISAM tables.
try {
$conn->autocommit(FALSE); // i.e., start transaction
// assume that the TABLE groups has an auto_increment id field
$query = "INSERT INTO groups (name) ";
$qu...
MySQL DISTINCT on a GROUP_CONCAT()
I am doing SELECT GROUP_CONCAT(categories SEPARATOR ' ') FROM table . Sample data below:
6 Answers
...