IMAGE/SQL: Issues and answers concerning SQL tables

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3.2 What are the key elements of security in SQL (continued)?

Key points

• HOW
  • The GRANT statement gives specified authority to one or more users or authorization groups. You can grant authorities on either tables or views (which are described below).

  • The REVOKE statement takes away authority that was previously granted.

  • In TurboIMAGE, a class can be given access to either an entire data set or a subset of data items from a data set.

    In SQL, a USER or GROUP can be given access to either an entire table or a subset of columns or rows from the table. To give access to a subset, the DBA can create a view. Think of a view as a filter that sits on top of the table. The CREATE VIEW statement is used to create a view on a table (or even on a another view).

    isql => CREATE PUBLIC TABLE Parts.Vendors 
    > (PartNumber   char(16),
    >  VendorNumber INTEGER,
    >  VendorCode   INTEGER)
    > IN partsfileset;
    
    isql => CREATE VIEW Parts.SpecialVendors 
    > as SELECT PartNumber,VendorNumber FROM Parts.Vendors 
    > where VendorCode = 5
    > IN partsfileset;
    
    ...
    
    isql => select * from Parts.Vendors;      /* THIS IS THE TABLE */
    ----------------+------------+-----------
    PARTNUMBER      |VENDORNUMBER|VENDORCODE
    ----------------+------------+-----------
    1123-P-01       |        9001|          5
    1133-P-01       |        9002|          4
    1143-P-01       |        9003|          1
    1153-P-01       |        9004|          5 
    1223-MU-01      |        9025|          5
    1233-MU-01      |        9006|          4
    1243-MU-01      |        9018|          1
    
    
    isql => select * from Parts.SpecialVendors;/* THIS IS THE VIEW */
    ----------------+------------
    PARTNUMBER      |VENDORNUMBER
    ----------------+------------
    1123-P-01       |        9001
    1153-P-01       |        9004
    1223-MU-01      |        9025
    

Page last updated on November 29, 1995