SQL is in practice for more than three decades now, which is admired by the IT industry as the default RDBMS (relational database management system) language. In fact, unlike many of them think about it, SQL is not a programming language, but a standard protocol which allows the database administrators to create any procedural extensions that serve all functionality of a full-fledged programming language.
SQL had several updates overtime and got further simplified and standardized to strength it for better data management and querying in any relational database. Even though there are many versions of database languages, SQL based for Oracle implementation is considered to be the most popular DBMS language nowadays. It is widely used for DB-related development. However, one major complaint about SQL is that it’s getting more complicated now with the requirement of meeting the challenge of big data management, etc.
On knowing further about SQL, we have to consider the sublanguages of SQL which are used to meet specific database functions.
- Data Definition Language or DDL is to define the data structures in a particular database appropriately. You can use DDL statements in order to create, update, or delete the database objects.
- Data Manipulation Language or DML can be used to change the stored data and raise queries to retrieve data. Typical DML statements are for selection, insertion, updating, and deletion of the table data.
- Data Control Language or DCL will restrict accesses to the database. These statements will assign privileges to various users in terms of applying different DML and DDL commands on database objects.
- Transaction Control Language or TCL is to control the transaction processing in the databases. Typical TCL statements can be used to apply various changes initiated by transactions, or undo them and set the save-points in order to divide transactions into different parts.
SQL following a declarative programming style in which each of the statement describes the exact action requires and the DBMS implement it to plan and execute the necessary operations. However, when it comes to SQL programming, the developers should understand the way how different database management systems process the SQL statements to create efficient execution plans.
SQL server RDBMS concepts
Understanding a database
Before getting into the SQL server, it is ideal to primarily understand a database as a common place to store, update, and retrieve structured data. The advanced database services as offered by RemoteDBA.com also lets the business administrator manipulate the data on retrieval in an easily understandable and analyzable manner. There are various SQL databases in practice to store, organize, and retrieve information in various formats.
As we have seen above, RDBMS or Relational Databases Management Systems are the most popular database types. In these types of databases, data is strictly structured and grouped based on the type of data in tables with columns and rows as like in a spreadsheet. Apart from categorizing data according to structure, RDBMS also lets the users create the relationships. This establishes links between various data types.
Concept of normalization vs. denormalization
- Normalization is a database technique which will help admins to minimize, if not eradicating, the possibility of data duplication. This approach will help reduce data errors as a result of the duplication of the same information.
- Denormalization is just the opposite process of normalization, in which the data is duplicated, but purposefully. Sometimes, it becomes essential to ensure better performance compared to normalized DBs. However, this will increase the cost in terms of the size of the database. Denormalization is found useful then the paramount consideration is for retrieval speed as in case of databases for reporting purpose etc.
SQL Server Relational Database concept
The developers using SQL Server for data management may benefit from the below terminology and functionalities.
The primary benefit of storing database in a structured manner is to retrieve the exact information needed quickly when needed. When preparing a DB query, it is possible for the DBAs to set criteria to retrieve the exact rows. On the other hand, this search process will take a lot of time if the DBMS has to scan the entire sets of data in a table to get the exact information needed. In typical relational databases, there may be millions of rows, and the retrieval process may take many hours. So, in order to improve retrieval performance, a table can be set with many indexes. Each of these indexes may enable a faster look-up for the row.
There are two different types of keys for the databases related to Microsoft SQL Server. It is the primary key and foreign key. The primary key is a single column and the group of various columns known as a compound key. These can help identify several rows in the table. All tables in an SQL database can have a unique primary key. Specifying this, there won’t be two rows in a single table containing matching data per columns of the primary key. The foreign keys can be used while defining the relationships between different tables. It primarily defines a single or group of columns in relation to the primary key representing that of another table. This defines the link between the two tables.
These are the rules which are applicable to database information. Constraints are used to enforce the typical business rules on tabular data. Constraints will reject an attempt to create a new row or date if the input is not matching to the set rule, and thereby ensure better database compliance.
IT is meant to create virtual tables. A typical view can gather needed info from various sources and present it as a single table. The queries information will get filtered to remove the unwanted information and the displayed.
- Stored procedure
A stored procedure is statements to be executed when needed. These can create custom programs in the databases of SQL Server. Stored procedures can be single queries to return data or to update the rows, or may be complex programs with conditional structured and looping needs.
By understanding these fundamentals of SQL server programming, you can move on to creating, populating, and manipulating SQL databases on MS SQL Server.