How do you get the first 10 rows in Db2?

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How do you get the first 10 rows in Db2?

To return only the rows of the employee table for those 20 employees, you can write a query as shown in the following example: SELECT LASTNAME, FIRSTNAME, EMPNO, SALARY FROM EMP ORDER BY SALARY DESC FETCH FIRST 20 ROWS ONLY; You can also use FETCH FIRST n ROWS ONLY within a subquery.

How do I SELECT a specific row in Db2?

select * from ( select istore, row_number() over (order by something) as rn from store ) t where rn = 2; Replace something with a column name that defines the order of your rows. Without any ordering there is no such thing as “the second row”.

How do I run a SELECT query in Db2?

Db2 SELECT

SELECT select_list FROM table_name;
SELECT title FROM books;
SELECT title, isbn FROM books;
SELECT book_id, title, total_pages, rating, isbn, published_date, publisher_id FROM books;
SELECT * FROM books;
SELECT expression FROM sysibm.sysdummy1;
SELECT CURRENT_DATE FROM sysibm.sysdummy1;

What is fetch in Db2?

The FETCH statement positions a cursor on a row of its result table. It can return zero, one, or multiple rows and assigns the values of the rows to variables if there is a target specification. Invocation. This statement can only be embedded in an application program.

What is optimize for 1 row in DB2?

OPTIMIZE FOR 1 ROW tells Db2 to select an access path that returns the first qualifying row quickly. Use FETCH FIRST n ROWS ONLY clause to limit the number of rows in the result table to n rows.

What is cursor in DB2?

Db2 has a mechanism called a cursor . Using a cursor is like keeping your finger on a particular line of text on a printed page. In Db2, an application program uses a cursor to point to one or more rows in a set of rows that are retrieved from a table.

What is Rownum in DB2?

What is ROW_NUMBER()? ROW_NUMBER() is a function that generates a psuedo-column containing consecutive numbers starting from 1 and counting up for each row of returned results (hence the name of ROW_NUMBER() ).

What SQL is used in Db2?

The language that you use to access the data in Db2 tables is the structured query language (SQL). SQL is a standardized language for defining and manipulating data in a relational database. The language consists of SQL statements.

What is with ur in DB2?

Using “with ur” on the end of a query tells DB2 that you want to use the Uncommitted Read isolation level. While Uncommitted Read is the least likely of all the isolation levels to acquire locks, it also can read data that has not been committed in the database.

What is optimization in DB2?

The OPTIMIZE FOR N ROWS is a DB2 clause which we can add in the query to give priority for the retrieval of the first few rows only. This clause will enable the optimizer to choose the access path that minimizes the response time for fetching first few rows.

What is Rowset in DB2?

A rowset-positioned cursor is a cursor that can return one or more rows for a single fetch operation. The cursor is positioned on the set of rows that are to be fetched.

How to fetch last n rows only in DB2?

The join method could change.

An index that matches the ORDER BY clause is more likely to be picked.

List prefetch is less likely to be picked.

Sequential prefetch is less likely to be requested by DB2 because it infers that you only want to see a small number of rows.

Where to find my tables on DB2?

select t.tabschema as schema_name, t.tabname as table_name from syscat.tables t where t.type = ‘T’ and t.tabname = ‘XGOREV’ order by schema_name, table_name; Columns. schema_name – name of schema table was found in; table_name – name of table (redundant as it should be exactly the same as provided) Rows. One row represents a table

How to find schema of a table in DB2?

– One row represents one table – Scope of rows: all tables in the schema – Ordered by table name

Can you access the DB2 directory table using SQL?

DB2 directory. Introduction to DB2 for z/OS. The DB2® directory contains information that DB2 uses during normal operation. You cannot access the directory by using SQL, although much of the same information is contained in the DB2 catalog, for which you can submit queries. The structures in the directory are not described in the DB2 catalog.