How do I fetch top 10 posts in PostgreSQL?

Returning TOP N Records

  1. Microsoft SQL Server SELECT TOP 10 column FROM table.
  2. PostgreSQL and MySQL SELECT column FROM table LIMIT 10.
  3. Oracle SELECT column FROM table WHERE ROWNUM <= 10.
  4. Sybase SET rowcount 10 SELECT column FROM table.
  5. Firebird SELECT FIRST 10 column FROM table.

What is Postgres SELECT 1?

select 1 from table will return the constant 1 for every row of the table. It’s useful when you want to cheaply determine if record matches your where clause and/or join .

How do you SELECT top 1 record in each group in SQL?

[InventoryAllocations] ORDER BY ROW_NUMBER() OVER(PARTITION BY DocumentID ORDER BY [RecordTimeStamp] DESC); TOP 1 works with WITH TIES here. WITH TIES means that when ORDER BY = 1 , then SELECT takes this record (because of TOP 1 ) and all others that have ORDER BY = 1 (because of WITH TIES ).

How do I limit records in PostgreSQL?

PostgreSQL LIMIT is an optional clause of the SELECT statement that constrains the number of rows returned by the query. The statement returns row_count rows generated by the query. If row_count is zero, the query returns an empty set.

How do you fetch a list of employees with the same salary?

Write a query to display employee records having same salary?

  1. Ashutosh Srivastava. Answered On : Sep 21st, 2007.
  2. Select * from emp where sal in( select sal from emp where rowid not in( select max(rowid) from emp group by sal))

How do I select top 10 records in SQL Server?

Example – Using TOP PERCENT keyword SELECT TOP(10) PERCENT employee_id, last_name, first_name FROM employees WHERE last_name = ‘Anderson’ ORDER BY employee_id; This SQL Server SELECT TOP example would select the first 10% of the records from the full result set.

What select 1 means?

The statement ‘select 1’ from any table name means that it returns only 1. For example, If any table has 4 records then it will return 1 four times.

What is the difference between select 1 and select *?

There is one essential difference between the use of SELECT * and SELECT 1. SELECT * will expand the column list and then throw what isn’t needed out. … The compilation of the query will simply determine which columns are relevant and to be used. With SELECT 1, this step isn’t performed during compilation..

What does select 1 from dual mean?

In your case, SELECT 1 FROM DUAL; will simply returns 1 . You need it because the INSERT ALL syntax demands a SELECT clause but you are not querying the input values from a table.

How do I get top 1 records in SQL?

The SQL SELECT TOP Clause

  1. SQL Server / MS Access Syntax: SELECT TOP numberpercent column_name(s) FROM table_name. …
  2. MySQL Syntax: SELECT column_name(s) FROM table_name. …
  3. Oracle 12 Syntax: SELECT column_name(s) FROM table_name. …
  4. Older Oracle Syntax: SELECT column_name(s) …
  5. Older Oracle Syntax (with ORDER BY): SELECT *

Can we use top with Group By clause?

A Top N query is one that fetches the top records, ordered by some value, in descending order. Typically, these are accomplished using the TOP or LIMIT clause. … The GROUP BY clause can help with that, but it is limited to the single top result for each group.

What is the difference between rank and Dense_rank?

RANK and DENSE_RANK will assign the grades the same rank depending on how they fall compared to the other values. However, RANK will then skip the next available ranking value whereas DENSE_RANK would still use the next chronological ranking value.

What is offset in PostgreSQL?

OFFSET says to skip that many rows before beginning to return rows. OFFSET 0 is the same as omitting the OFFSET clause. If both OFFSET and LIMIT appear, then OFFSET rows are skipped before starting to count the LIMIT rows that are returned.

What is limit and offset in Postgres?

LIMIT will retrieve only the number of records specified after the LIMIT keyword, unless the query itself returns fewer records than the number specified by LIMIT. OFFSET is used to skip the number of records from the results.

What is Rownum equivalent in Postgres?

Postgresql does not have an equivalent of Oracle’s ROWNUM. In many cases you can achieve the same result by using LIMIT and OFFSET in your query.

How can I get 10th highest salary in SQL?

Select Emp_name from table_name where Salary =(Select Salary from table_name order by Salary DESC limit n-1,1); There can be another question like find Nth Lowest Salary . In order to that , just reverse order using ASC ( if you don’t specify by default column will be ordered in ascending order).

Where can I find employees that hired in the last month?

How can find maximum salary and name in SQL?

SELECT name, MAX(salary) AS salary FROM employee WHERE salary IN (SELECT salary FROM employee MINUS SELECT MAX(salary) FROM employee); SELECT name, MAX(salary) AS salary FROM employee WHERE salary <> (SELECT MAX(salary) FROM employee);

How do you select the top 5 values in SQL?

SQL SELECT TOP Clause

  1. SQL Server / MS Access Syntax. SELECT TOP numberpercent column_name(s) FROM table_name;
  2. MySQL Syntax. SELECT column_name(s) FROM table_name. LIMIT number;
  3. Example. SELECT * FROM Persons. LIMIT 5;
  4. Oracle Syntax. SELECT column_name(s) FROM table_name. WHERE ROWNUM <= number;
  5. Example. SELECT * FROM Persons.

How do I select the latest record in SQL?

But there are ways to get the last record in MySql, SQL Server, Oracle etc. databases. … Oracle syntax:

  1. SELECT column_name FROM table_name.
  2. ORDER BY column_name DESC.
  3. WHERE ROWNUM <=1;

How do I get top 10 in MySQL?

To select first 10 elements from a database using SQL ORDER BY clause with LIMIT 10. Insert some records in the table using insert command. Display all records from the table using select statement. Here is the alternate query to select first 10 elements.

What does SELECT * from do?

An asterisk ( * ) can be used to specify that the query should return all columns of the queried tables. SELECT is the most complex statement in SQL, with optional keywords and clauses that include: The FROM clause, which indicates the table(s) to retrieve data from.

What is the use of 1 1 in SQL?

The 1=1 is ignored by always all rdbms. There is no tradeoff executing a query with WHERE 1=1. Building dynamic WHERE conditions, like ORM frameworks or other do very often, it is easier to append the real where conditions because you avoid checking for prepending an AND to the current condition.

What does 1 mean in SQL?

WHERE 1 is a synonym for true or everything. It’s a shortcut so they don’t have to remove the where clause from the generated SQL.

Where exists select 1 or select *?

There is no difference between EXISTS with SELECT * and SELECT 1. SQL Server generates similar execution plans in both scenarios. EXISTS returns true if the subquery returns one or more records. Even if it returns NULL or 1/0.

What is the difference between select and select * in SQL?

SELECT * will return 100 columns * 10 bytes worth of data while SELECT ColA, ColB, ColC will return 3 columns * 10 bytes worth of data. This is a huge size difference in the amount of data that is being passed back across the wire.

What is the meaning of select * from table?

Select * from any table will fetch and display all the column in that table, while Select 1 from any table will display one row with 1 without any column name.

What is the output of the query select 1 1 from dual?

When you select an expression say 1 from a table (can be dual or any other table), it will return the expression depending on the number of rows in the table. Eg:- Select 1 from dual; returns 1 as there is only one record in dual. Here is a table called TAB1 that has 3 rows. I hope this helps.

What is select from dual?

DUAL is a table automatically created by Oracle Database along with the data dictionary. Selecting from the DUAL table is useful for computing a constant expression with the SELECT statement. … Because DUAL has only one row, the constant is returned only once.

Can we delete DUAL table in Oracle?

Can We Drop The DUAL Table in Oracle? Technically you can, but you shouldn’t. Messing with the DUAL table or any other table in the SYS schema can break your database. There is no need to drop this table.