Structured Query Language (sql)
Gbogbo ọrọ náà
A database with a million records is useless unless you can ask it a question and get the four rows you actually wanted. The language for asking is SQL, and its central idea is unusual for a programming language: you describe what you want rather than how to find it. You do not write a loop over a million records. You say which fields, from which tables, matching which condition, and the database works out the rest.
This lesson covers the commands the specification names. You will learn to retrieve data with SELECT, FROM and WHERE, including queries that draw on two tables at once; to add a record with INSERT INTO; and to edit and delete data with UPDATE and DELETE FROM. You will also learn the single most consequential detail in the whole topic, which is what happens to an UPDATE or a DELETE that is missing its WHERE clause.
Ebumnobi
- Be able to use SQL to retrieve data from a relational database, using the commands:
- SELECT
- FROM
- WHERE. Be able to use SQL to insert data into a relational database using INSERT INTO. Be able to use the SQL commands UPDATE and DELETE FROM to edit and delete data in a database.
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Nnyocha Ọmụmụ
Ekele diri gi maka imecha ihe karịrị na Structured Query Language (sql). Ugbu a na ị na-enyochakwa isi echiche na echiche ndị dị mkpa, ọ bụ oge iji nwalee ihe ị ma. Ngwa a na-enye ụdị ajụjụ ọmụmụ dị iche iche emebere iji kwado nghọta gị wee nyere gị aka ịmata otú ị ghọtara ihe ndị a kụziri.
Ị ga-ahụ ngwakọta nke ụdị ajụjụ dị iche iche, gụnyere ajụjụ chọrọ ịhọrọ otu n’ime ọtụtụ azịza, ajụjụ chọrọ mkpirisi azịza, na ajụjụ ede ede. A na-arụpụta ajụjụ ọ bụla nke ọma iji nwalee akụkụ dị iche iche nke ihe ọmụma gị na nkà nke ịtụgharị uche.
Jiri akụkụ a nke nyocha ka ohere iji kụziere ihe ị matara banyere isiokwu ahụ ma chọpụta ebe ọ bụla ị nwere ike ịchọ ọmụmụ ihe ọzọ. Ekwela ka nsogbu ọ bụla ị na-eche ihu mee ka ị daa mba; kama, lee ha anya dị ka ohere maka ịzụlite onwe gị na imeziwanye.
- Which SQL clause states which records a query should return? A. SELECT B. FROM C. WHERE D. INSERT INTO Answer: C
- Which query correctly finds the names of all cats and all birds in a table called Pet? A. SELECT Name FROM Pet WHERE TypeOfAnimal = 'Cat' AND TypeOfAnimal = 'Bird' B. SELECT Name FROM Pet WHERE TypeOfAnimal = 'Cat' OR TypeOfAnimal = 'Bird' C. SELECT Name FROM Pet WHERE TypeOfAnimal = Cat OR Bird D. SELECT Name FROM Pet WHERE TypeOfAnimal = 'Cat' OR 'Bird' Answer: B
- What does the statement DELETE FROM Booking do if it has no WHERE clause? A. Nothing, because a WHERE clause is required B. It deletes the first record only C. It deletes every record in the Booking table D. It deletes the Booking table's field names Answer: C
- Which command is used to change the value already stored in a field? A. SELECT B. INSERT INTO C. UPDATE D. DELETE FROM Answer: C
- In a query drawing on two tables, what is the purpose of a condition such as Pet.PetID = Appointment.PetID? A. It sorts the results into order B. It matches each record in one table with the correct record in the other C. It deletes records that appear in both tables D. It renames a field Answer: B
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Meecha Ajụjụ Ule Ọmarịcha
Ị chọrọ ime ajụjụ ule ọmarịcha gbasara Structured Query Language (sql)? Budata ngwa Green Bridge CBT iji nweta ajụjụ ule ọmarịcha na nyocha zuru ezu gbasara isiokwu a.
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