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    features and uses of SQL

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    Outline the specific features and uses of SQL. Put in examples of each point or feature that you explain.

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    https://brainmass.com/computer-science/java/features-uses-sql-56123

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    Please see the attached file.

    SQL

    (Structured Query Language) Pronounced "S-Q-L" a language used to interrogate and process data in a relational database. Originally developed by IBM for its mainframes, all database systems designed for client/server environments support SQL. SQL commands can be used to interactively work with a database or can be embedded within a programming language to interface to a database. Programming extensions to SQL have turned it into a full-blown database programming language, and all major database management systems (DBMSs) support the language.

    When SQL was not developed File-processing System was very popular for processing and storing the data. But some of the major disadvantages of File-processing System like Data redundancy and inconsistency, difficulty in accessing data, data isolation, concurrent access anomalies lead to the development of SQL.

    SQL is a non-procedural language and a language that all commercial RDBMS implementations understand.

    Example:
    The following SQL query selects customers with credit limits of at least $5,000 and puts them into sequence from highest credit limit to lowest. The bold words are SQL verbs.

    select name, city, state, zipcode
    from customer
    where creditlimit > 4999
    order by creditlimit desc

    Data Types:
    There are various data types that SQL supports like:
    Integers

    Decimal numbers

    Floating point numbers---- FLOAT

    Fixed length character strings---- CHAR (len)
    Fixed length character data of length len bytes. This should be used for fixed length data.

    Variable length character strings --- Varchar2(len)
    Variable length character string having maximum length len bytes. We must pecify the size
    Dates-----DATE

    SQL has three flavors of statements. The DDL, DML and DCL.

    DDL is Data Definition Language statements. Some examples:
    CREATE - to create objects in the database
    ALTER - alters the structure of the database
    DROP - delete objects from the database
    TRUNCATE - remove all records from a table, including all spaces allocated for the records are removed
    COMMENT - add comments to the data dictionary
    GRANT - gives user's access privileges to database
    REVOKE - withdraw access privileges given with the GRANT command

    DML is Data Manipulation Language statements. Some examples:
    SELECT - retrieve data from the a database
    INSERT - insert data into a table
    UPDATE - updates existing data within a table
    DELETE - deletes all records from a table, the space for the records remain
    CALL - call a PL/SQL or Java subprogram
    EXPLAIN PLAN - explain access path to data
    LOCK TABLE - control concurrency

    DCL is Data Control Language statements. Some examples:
    COMMIT - save work done
    SAVEPOINT - identify a point in a transaction to which you can later roll back
    ROLLBACK - restore database to original since the last COMMIT
    SET TRANSACTION - Change transaction options like what rollback segment to use

    Set Operational Features:

    The SQL operations union, intersect ...

    Solution Summary

    This job examines features and uses of SQL.

    $2.19