http://www.cbseguess.com/ Guess Paper – 2010 Class – XII Subject – Informatics Practices PL/SQL PL/SQL is a Procedural Language. It is a procedural extension of Oracle-SQL that offers language constructs similar to those in imper ative programming languages. PL/SQL allows its users to develo p complex databa se applications that require the usage of control structures and procedural elements such as procedures, function, modules etc . Limitations of SQL: 1. It does n’t of fer s proc edur al capa bil iti es. 2. No er ror handli ng pr ocedur es ar e supported by SQL. 3. Pro ces sin g in SQL is Time -Con suming. 4. Net wor k tr aff ic i s hi gh i n SQL. 5. SQL comman ds can ’t be shared by multi ple app lications. Advantages of PL/SQL over SQL: 1. It has procedural c apa bil iti es. 2. It supports e rro r-handl ing pr oced ures. 3. Proce ssing in P L/SQL is less time consuming. 4. Use of P L/SQL reduces the network tr affic. 5. PL/S QL promotes sh aring o f progr ams by multi ple appl icati ons. Block: PL/SQL block is a set of related procedural SQL statements, enclosed within the reserved words BEGIN and END. PL/SQL supports two types of blocks. 1. Anon ymous Bl oc k: these are the block without header. They are not stored in the database. 2. Named Block: these are the block having headers or labels. They are stored in the database. Named blocks can be procedures, functions or triggers. Reserved words: are the predefined words that are assigned some specific and special meaning. These words can’t be used as identifiers (variable, function name, procedure name etc.) in PL/SQL. E.g Declare, Begin, For, Loop, End, End Loop, End If, Then Etc. Comment: comments are the non-executable statements in PL/SQL. These are used to increase the readability of the program. There are two types of comments supported by PL/SQL. 1. Si ng le l ine comment: these comments start with the sign ‘- -‘ 2. Mul tip le Lin e Comment: these comments start with /* and end with */. Identifier: refers to the name of the object in PL/SQL. E.g Variable, Cursors, Procedures, Functions etc. Delimiters : are the symbols that have special meaning in PL/SQL. E.g assignment operator( := ), concatenation operator( || ), range( .. ), +, -, *, /, exponential( ** ) etc. Datatypes specify the storage format and valid range of value for a variable. PL/SQL provides following datatypes: 1. Scalar type: it is atomic means it is not made up of other datatypes. e.g CHAR, VARCHAR2, NUMBER, DATE, BOOLEAN, LONG. 2. Composite type: it is made up of other datatypes. it has some internal components that can be manipulated individually. E.g. TABLE, RECORD. ------------------------------------------------------------------------------------------------------- www.cbseguess.com Other Educational Portals www.icseguess.com | www.ignouguess.com | www.dulife.com | www.magicsense.com
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