CODEWITHSUNDEEP
sqladhoc-queries
zihado
zihado

Reputation: 2381

What is Ad Hoc Query?

I'm reading a book about SQL. In that book there's the term Ad Hoc Query, which I don't understand.

What exactly is an ad hoc query?

Upvotes: 209

Views: 210954

Answers (11)

Rohan Devaki
Rohan Devaki

Reputation: 3279

Ad-hoc Query -

  • this type of query is designed for a "particular purpose,“ which is in contrast to a predefined query, which has the same output value on every execution.
  • An ad hoc query command executed in each time, but the result is different, depending on the value of the variable.
  • It cannot be predetermined and usually comes under dynamic programming SQL query.
  • An ad hoc query is short lived and is created at runtime.

Upvotes: 1

A.HADDAD
A.HADDAD

Reputation: 1906

Ad-hoc Statments are just T-SQL Statements that it has a Where Clause , and that Where clause can actualy have a literal like :

Select * from member where member_no=285;

or a variable :

declare @mno INT=285;
Select * from member where member_no=@mno

Upvotes: 1

Eliot G York
Eliot G York

Reputation: 161

An Ad-hoc query is one created to provide a specific recordset from any or multiple merged tables available on the DB server. These queries usually serve a single-use purpose, and may not be necessary to incorporate into any stored procedure to run again in the future.

Ad-hoc scenario: You receive a request for a specific subset of data with a unique set of variables. If there is no pre-written query that can provide the necessary results, you must write an Ad-hoc query to generate the recordset results.

Beyond a single use Ad-hoc query are stored procedures; i.e. queries which are stored within the DB interface tool. These stored procedures can then be executed in sequence within a module or macro to accomplish a predefined task either on demand, on a schedule, or triggered by another event.

Stored Procedure scenario: Every month you need to generate a report from the same set of tables and with the same variables (these variables may be specific predefined values, computed values such as “end of current month”, or a user’s input values). You would created the procedure as an ad-hoc query the first time. After testing the results to ensure accuracy, you may chose to deploy this query. You would then store the query or series of queries in a module or macro to run again as needed.

Upvotes: 5

Ketan Anand
Ketan Anand

Reputation: 11

An Ad-Hoc Query is a query that cannot be determined prior to the moment the query is issued. It is created in order to get information when need arises and it consists of dynamically constructed SQL which is usually constructed by desktop-resident query tools. An ad hoc query does not reside in the computer or the database manager but is dynamically created depending on the needs of the data user.

In SQL, an ad hoc query is a loosely typed command/query whose value depends upon some variable. Each time the command is executed, the result is different, depending on the value of the variable. It cannot be predetermined and usually comes under dynamic programming SQL query. An ad hoc query is short lived and is created at runtime.

Upvotes: 1

Sanyog Tiwari
Sanyog Tiwari

Reputation: 31

Ad hoc query is type of computer definition. Which means this query is specially design to obtain any information when it is only needed. Predefined. refer this https://www.youtube.com/watch?v=0c8JEKmVXhU

Upvotes: -7

Ravi
Ravi

Reputation: 7

An Ad-Hoc query is:

  1. Pre-planned question.
  2. Pre-scheduled question.
  3. spur of the moment question.
  4. Question that will not return any results.

Upvotes: -5

user3134258
user3134258

Reputation: 1

Ad hoc queries are those that are not already defined that are not needed on a regular basis, so they're not included in the typical set of reports or queries

Upvotes: 0

haltunbay
haltunbay

Reputation: 645

An Ad-Hoc Query is a query that cannot be determined prior to the moment the query is issued. It is created in order to get information when need arises and it consists of dynamically constructed SQL which is usually constructed by desktop-resident query tools.

Check: http://www.learn.geekinterview.com/data-warehouse/dw-basics/what-is-an-ad-hoc-query.html

Upvotes: 32

xli
xli

Reputation: 2510

Also want to add that ad hoc query is vulnerable to SQL injection attacks. We should try to avoid using it and use parameterized SQLs instead (like PreparedStatement in Java).

Upvotes: 0

Expansion
Expansion

Reputation: 5

In Sql Server "Ad Hoc Query" is also used for Ad Hoc Distributed Queries. These are ad hoc queries on an other server via OpenRowset or OpenDatasource. Ad Hoc Distributed Queries are only allowed after configuring so. This is a Server configuration option.

Upvotes: -8

David Hedlund
David Hedlund

Reputation: 129792

Ad hoc is latin for "for this purpose". You might call it an "on the fly" query, or a "just so" query. It's the kind of SQL query you just loosely type out where you need it

var newSqlQuery = "SELECT * FROM table WHERE id = " + myId;

...which is an entirely different query each time that line of code is executed, depending on the value of myId. The opposite of an ad hoc query is a predefined query such as a Stored Procedure, where you have created a single query for the entire generalized purpose of selecting from that table (say), and pass the ID as a variable.

Upvotes: 267

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