SQL: Brief Overview
Structured Query Language ( SQL ) is a brawny, non-procedural, database linguistic process which is used in the management of relational databases. Developed by IBM inquiry, it is highly portable, upgradeable and offers a gamey degree of abstraction when compared with adjective languages. Through SQL, end-users can interact with respective database management systems as per their handiness .
PL/SQL: Brief Overview
PL/SQL is a knock-down adjective speech that extends adjective constructs to SQL statements. It is known for its high serve amphetamine and mistake handle capabilities.
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In PL/SQL, blocks of code or multiple statements are executed at once which consist of functions, triggers, packages, etc, that enhance the functionality of an process. This besides helps in reducing network traffic. Learn more about PLSQL developer wage in India .
The block-structured speech has program blocks that can be of two types :
- anonymous Blocks – when a freeze of code is not stored in your database .
- Stored procedures – when a block is named and stored as a parse representation in your database .
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Key Differences Between SQL and PL/SQL
- SQL is a structural Query Language created to manipulate relational databases. It is a declarative, detail-oriented lyric. Whereas, PL/SQL is a procedural Language/Structured Query Language that uses SQL as its database. It is an application-oriented lyric .
- There are no variables in SQL whereas PL/SQL has variables constraints, data types, etc .
- In SQL, we use DDL and DML to write queries and commands whereas with PL/SQL, code blocks containing functions, triggers, variables, master structures ( for loop, while ), conditional statements ( if..then..else ) are written .
- In SQL, a single operation or question can be executed at a time. however, In PL/SQL, multiple operations or an stallion block of close can be executed at once. This results in reduce network traffic .
- It is possible to embed in a PL/SQL block whereas the diametric can ’ deoxythymidine monophosphate be done .
- Unlike PL/SQL, there is directly interaction between SQL and the database server
- PL/SQL offers high processing speed while performing manipulation of large volumes of data. This can ’ t be achieved with SQL .
SQL vs PLSQL: Execution
Execution in SQL
We have statements in SQL which are basically instructions through which a user tells SQL what they want to be done. SQL then compiles these instructions and navigates the database to perform the undertaking .
Every process needs to be executed using SQL statements. farther, there are certain words in SQL that are reserved to perform a particular job. For exemplify, SELECT, UPDATE, DELETE. These can not be used as names for any early determination. ( note : Almost all operations are performed by SQL but there are besides tools and apps available to make SQL ’ s undertaking easier. )
There are six types of statements in SQL .
- Data Manipulation Language statements ( DML )
- Data Definition Language statements ( DDL )
- transaction Control statements
- Session Control statements
- System Control statements
- Embedded SQL statements
Data Manipulation Language statements and Data Definition Language statements are most normally used in SQL queries. so, let ’ s take a brief front at the two :
Data Manipulation Statements (DML)
DML statements comprise the likes of SELECT, DELETE, INSERT, UPDATE. They are basically used to manipulate a database. Using DML statements, you can perform operations like erase or add rows, select a particular table or more than one table, select a view, updates values in existing rows, etc .
here is an model :
SELECT ename, mgr, comm + sal FROM emp ;
INSERT INTO emp VALUES
( 4321, ‘ ROBERT ’, ‘ ACCOUNTANT ’, 9876, ’ 14-JAN-1982′, 1600, 500, 30 ) ;
edit FROM emp WHERE ename IN ( ‘ WARD ’, ’ JONES ’ ) ;
Data Definition Statements ( DDL )
Using DDL statements, you can create a schema object, alter its structure or rename or drop it. You can besides delete all the data in a schema object without having to delete the entire structure. There are several other operations that you can perform using DDL statements .
Some DDL statements include CREATE, ALTER, DROP, TRUNCATE, ANALYSE, COMMENT, to mention a few .
here is an model :
CREATE mesa plants
( COMMON_NAME VARCHAR2 ( 15 ), LATIN_NAME VARCHAR2 ( 40 ) ) ;
DROP TABLE plants ;
GRANT SELECT ON emp TO Scott ;
REVOKE DELETE ON emp FROM Scott ;
Execution in PL/SQL
Procedures are stored in the database to be called as required by an application. They can besides be called from another PL/SQL obstruct ( anonymous or stored ). As a routine is called by an application, it is compiled and loaded into the System Global Area where PL/SQL and SQL process them using their respective executors .
Every program unit of measurement a PL/SQL is present in the form of a block, which consists of declarations and statements. It can be nested to include another block .
They are designated by the following keywords
- DECLARE – for variables, subprograms and local types. A indicative mood share of a pulley ends on completion of execution to avoid clutter .
- BEGIN – contains statements which have entree to the declarations. This is the feasible part of the block .
- EXCEPTION – any exceptions raised during execution are taken manage of here. The exception handling share of the block is normally placed at the end of a routine to eliminate exceptions in the lapp .
Another important aspect of PL/SQL is its control structures that aid you control the stream of statements. These are quite authoritative while writing Triggers .
They can be categorised into three types
- conditional control : This includes the IF-THEN-ELSE statements where if checks for a condition, ELSE indicates the action to perform and ELSE denotes what should be done if the condition is not dependable .
- iterative control : These include closed circuit statements using which you can perform an military action multiple times. FOR, WHILE and WHEN are included here .
- consecutive dominance : This is to let you move from one label to another without any conditions applied. ( GOTO argument )
Usage of SQL and PL/SQL
due to the detail-oriented nature of SQL and that it can immediately interact with the databases ), SQL statements are a great choice for creating analytic reports. Since it writes DML statements, it besides finds use in supporting applications where there is a indigence for childlike update. basically, it is designed for data manipulation and does equitable that .
PL/SQL is application-based and is chiefly used to design applications such as building user screens or creating back-end logic for web pages. SQL is creditworthy for providing data for these PL/SQL based applications. PL/SQL can be integrated with Java and PHP to create building complex logic .
As we know, PL/SQL is an extension of SQL and does what SQL does but on boastfully volumes of data using functions, control structures and triggers. SQL only deals with the what of carry through while PL/SQL even tells you how .
PL/SQL is a refine approach path to deal with building complex SQL problems. While SQL is better at data abstraction and portability, PL/SQL scores where performance and accelerate are concerned .
To conclude, it is obvious adding an supernumerary skill to your portfolio is always a commodity idea. A wise man once said, “ Knowledge never gets wasted. ” And, to take a short citation, that wise man is me.
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