大约有 40,000 项符合查询结果（耗时：0.0352秒） [XML]
PostgreSQL create table if not exists
..._mytable()
RETURNS void
LANGUAGE plpgsql AS
$func$
BEGIN
IF EXISTS (SELECT FROM pg_catalog.pg_tables
WHERE schemaname = 'myschema'
AND tablename = 'mytable') THEN
RAISE NOTICE 'Table myschema.mytable already exists.';
ELSE
CREATE TABLE myschema...
Row count with PDO
...
$sql = "SELECT count(*) FROM `table` WHERE foo = ?";
$result = $con->prepare($sql);
$result->execute([$bar]);
$number_of_rows = $result->fetchColumn();
Not the most elegant way to do it, plus it involves an extra query...
How to see the values of a table variable at debug time in T-SQL?
...
DECLARE @v XML = (SELECT * FROM <tablename> FOR XML AUTO)
Insert the above statement at the point where you want to view the table's contents. The table's contents will be rendered as XML in the locals window, or you can add @v to the...
Use a LIKE statement on SQL Server XML Datatype
If you have a varchar field you can easily do SELECT * FROM TABLE WHERE ColumnA LIKE '%Test%' to see if that column contains a certain string.
...
SQL update fields of one table from fields of another one
...ic SQL is totally non-standard PostgreSQL syntax.
DO
$do$
BEGIN
EXECUTE (
SELECT
'UPDATE b
SET (' || string_agg( quote_ident(column_name), ',') || ')
= (' || string_agg('a.' || quote_ident(column_name), ',') || ')
FROM a
WHERE b.id = 123
AND a.id = b.id'
FROM i...
MySQL Data - Best way to implement paging?
...e LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants (except when using prepared statements).
With two arguments, the first argument specifies the offset of the first ro...
How to reset sequence in postgres and fill id column with new data?
...
SELECT setval('seq', 1, FALSE) should do the same (here, the third argument, FALSE, does the magic, as it shows that nextval must be 1 instead of 2)
– Vasilen Donchev
Sep 22 '15 at 14:43...
Regex select all text between tags
What is the best way to select all the text between 2 tags - ex: the text between all the 'pre' tags on the page.
17 Answe...
add column to mysql table if it does not exist
...rade_database_1_0_to_2_0()
BEGIN
-- rename a table safely
IF NOT EXISTS( (SELECT * FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=DATABASE()
AND TABLE_NAME='my_old_table_name') ) THEN
RENAME TABLE
my_old_table_name TO my_new_table_name,
END IF;
-- add a column safely
IF NO...
How to select a node using XPath if sibling node has a specific value?
...
Q: How to select a node using XPath if sibling node has a specific value?
Because there are only "XPath Axes" for following-siblings and preceding-siblings, you can use one of them if the position is fixed.
But better:
Look for cc w...