大约有 40,000 项符合查询结果（耗时：0.0361秒） [XML]
COUNT(*) vs. COUNT(1) vs. COUNT(pk): which is better? [duplicate]
...for all your queries that need to count everything, even for joins, use *
SELECT boss.boss_id, COUNT(subordinate.*)
FROM boss
LEFT JOIN subordinate on subordinate.boss_id = boss.boss_id
GROUP BY boss.id
But don't use COUNT(*) for LEFT joins, as that will return 1 even if the subordinate table doe...
List all sequences in a Postgres db 8.1 with SQL
...
The following query gives names of all sequences.
SELECT c.relname FROM pg_class c WHERE c.relkind = 'S';
Typically a sequence is named as ${table}_id_seq. Simple regex pattern matching will give you the table name.
To get last value of a sequence use the following query:...
SQL Server CTE and recursion example
...The query finds all root nodes as described by WHERE ManagerID IS NULL
SELECT EmployeeID, FirstName, LastName, ManagerID, 1
FROM Employees
WHERE ManagerID IS NULL
-->>>>>>>>>>Block 1>>>>>>>>>>>>>>>>>
UNI...
How do I find duplicate values in a table in Oracle?
...then use a HAVING clause to find values that appear greater than one time.
SELECT column_name, COUNT(column_name)
FROM table_name
GROUP BY column_name
HAVING COUNT(column_name) > 1;
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SELECT * FROM X WHERE id IN (…) with Dapper ORM
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Dapper supports this directly. For example...
string sql = "SELECT * FROM SomeTable WHERE id IN @ids"
var results = conn.Query(sql, new { ids = new[] { 1, 2, 3, 4, 5 }});
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How to select rows that have current day's timestamp?
I am trying to select only today's records from a database table.
9 Answers
9
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Oracle SQL Query for listing all Schemas in a DB
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Using sqlplus
sqlplus / as sysdba
run:
SELECT *
FROM dba_users
Should you only want the usernames do the following:
SELECT username
FROM dba_users
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PostgreSQL Crosstab Query
... - not fit for missing attributes
crosstab(text) with 1 input parameter:
SELECT *
FROM crosstab(
'SELECT section, status, ct
FROM tbl
ORDER BY 1,2' -- needs to be "ORDER BY 1,2" here
) AS ct ("Section" text, "Active" int, "Inactive" int);
Returns:
Section | Active | Inacti...
How to calculate percentage with a SQL statement
...ultiplication of 100 in the wrong place and had some missing parenthesis.
Select Grade, (Count(Grade)* 100 / (Select Count(*) From MyTable)) as Score
From MyTable
Group By Grade
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HTML Form: Select-Option vs Datalist-Option
I was wondering what the differences are between Select-Option and Datalist-Option. Is there any situation in which it would be better to use one or the other? An example of each follows:
...