Database languages in dbms

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Database Languages and Interfaces The DBMS must provide appropriate languages and interfaces for each category of users. In this section we discuss the types of languages and interfaces provided by a DBMS and the user categories targeted by each interface. 1. DBMS Languages Once the design of a database is completed and a DBMS is chosen to implement the database, the first step is to specify conceptual and internal schemas for the database and any mappings between the two. In many DBMSs where no strict separation of levels is maintained, one language, called the data definition language ( DDL), is used by the DBA and by database designers to define both schemas. The DBMS will have a DDL compiler whose function is to process DDL statements in order to identify descriptions of the schema constructs and to store the schema description in the DBMS catalog. In DBMSs where a clear separation is maintained between the conceptual and internal levels, the DDL is used to specify the conceptual schema only. Another language, the storage definition language ( SDL), is used to specify the internal schema. The mappings between the two schemas may be specified in either one of these languages. In most relational DBMSs today, there is no specific language that performs the role of SDL. Instead, the internal schema is specified by a combination of functions, parameters, and specifications related to storage. These permit the DBA staff to control indexing choices and mapping of data to stor...

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A database schema defines how data is organized within a relational database; this is inclusive of logical constraints such as, table names, fields, data types, and the relationships between these entities. Schemas commonly use visual representations to communicate the architecture of the database, becoming the foundation for an organization’s data management discipline. This process of database schema design is also known as These data models serve a variety of roles, such as database users, database administrators, and programmers. For example, it can help database administrators manage normalization processes to avoid data duplication. Alternatively, it can enable analysts to navigate these data structures to conduct reporting or other valuable business analyses. These diagrams act as valuable documentation within the database management system (DBMS), ensuring alignment across various stakeholders. Database schema vs. database instance A database schema is considered the “blueprint” of a database which describes how the data may relate to other tables or other data models. However, the schema does not actually contain data. A sample of data from a database at a single moment in time is known as a database instance. It contains all the properties that the schema describes as data values. Since database instances are just a snapshot at a given moment, they’re likely to change over time, unlike database schemas. While the term schema is broadly used, it is commonly referr...

In the previous chapters, you have learned about the various forms of relational algebra and relational calculus and their uses with the database management system. In this chapter, you will get to know about the various forms of languages that are used to deal with the database. What are database Sub languages? A data sublanguage mainly has two parts: • Data Definition Language (DDL) and • Data Manipulation Language (DML). The Data Definition Language is used for specifying the database schema, and the Data Manipulation Language is used for both reading and updating the database. These languages are called data sub-languages as they do not include constructs for all computational requirements. Computation purposes include conditional or iterative statements that are supported by the high-level programming languages. Many DBMSs can embed the sublanguage is a high-level programming language such as 'Fortran,' 'C,' C++, Java, or Visual Basic. Here, the high-level language is sometimes referred to as the host language as it is acting as a host for this language. To compile the embedded file, the commands in the data sub-language are first detached from the host-language program and are substituted by function calls. The pre-processed file is then compiled and placed in an object module, which gets linked with a DBMS-specific library that is having the replaced functions and executed based on the requirement. Most data sub-languages also supply non-embedded or interactive comm...

Database Languages in DBMS • A DBMS has appropriate languages and interfaces to express database queries and updates. • Database languages can be used to read, store and update the data in the database. Types of Database Languages 1. Data Definition Language (DDL) • DDL stands for Data Definition Language. It is used to define database structure or pattern. • It is used to create schema, tables, indexes, constraints, etc. in the database. • Using the DDL statements, you can create the skeleton of the database. • Data definition language is used to store the information of metadata like the number of tables and schemas, their names, indexes, columns in each table, constraints, etc. Here are some tasks that come under DDL: • Create: It is used to create objects in the database. • Alter: It is used to alter the structure of the database. • Drop: It is used to delete objects from the database. • Truncate: It is used to remove all records from a table. • Rename: It is used to rename an object. • Comment: It is used to comment on the data dictionary. These commands are used to update the database schema that's why they come under Data definition language. 2. Data Manipulation Language (DML) DML stands for Data Manipulation Language. It is used for accessing and manipulating data in a database. It handles user requests. Here are some tasks that come under DML: • Select: It is used to retrieve data from a database. • Insert: It is used to insert data into a table. • Update: It is ...

SQL is a standard language for accessing and manipulating databases. What is SQL? • SQL stands for Structured Query Language • SQL lets you access and manipulate databases • SQL became a standard of the American National Standards Institute (ANSI) in 1986, and of the International Organization for Standardization (ISO) in 1987 What Can SQL do? • SQL can execute queries against a database • SQL can retrieve data from a database • SQL can insert records in a database • SQL can update records in a database • SQL can delete records from a database • SQL can create new databases • SQL can create new tables in a database • SQL can create stored procedures in a database • SQL can create views in a database • SQL can set permissions on tables, procedures, and views SQL is a Standard - BUT.... Although SQL is an ANSI/ISO standard, there are different versions of the SQL language. However, to be compliant with the ANSI standard, they all support at least the major commands (such as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar manner. Note: Most of the SQL database programs also have their own proprietary extensions in addition to the SQL standard! Using SQL in Your Web Site To build a web site that shows data from a database, you will need: • An RDBMS database program (i.e. MS Access, SQL Server, MySQL) • To use a server-side scripting language, like PHP or ASP • To use SQL to get the data you want • To use HTML / CSS to style the page RDBMS RDBMS stands for Relational Databa...

With the explosion of web and cloud technologies, databases have evolved from traditional relational databases to more advanced types of databases such as On top of that, databases are continuously handling mission-critical and sensitive data. When this is coupled with compliance requirements and the distributed nature of most data sets, managing databases has become highly complex. As a result, organizations require robust, secure, and user-friendly tools to maintain these databases. This is where database management systems come into play—by offering a platform to manage databases. Let’s take a look. What is a database management system? A database management system (DBMS) is a software tool that enables users to manage a database easily. It allows users to access and interact with the underlying data in the database. These actions can range from simply querying data to defining database schemas that fundamentally affect the database structure. Furthermore, DBMS allow users to interact with a database securely and concurrently without interfering with each user and while maintaining data integrity. Database tasks in a DBMS The typical database administrative tasks that can be performed using a DBMS include: • Configuring authentication and authorization. Easily configure user accounts, define access policies, modify restrictions, and access scopes. These operations allow administrators to limit access to underlying data, control user actions, and manage users in database...