SQL Tutorial > Understand Databases and Relationships

Database Relationships

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When two database tables are linked, one of them must have a foreign key that refers to the primary key of another table. A database entity is a person, place, thing, object, or any other item about which data is kept in the database in strict terms.

There are 3 different types of relations in the database:

  • one-to-one.
  • one-to-many, and.
  • many-to-many.

Database connections are associations between tables that are built by retrieving data using join statements.

A database is a collection of interconnected data. These data are kept in tables that are coupled to one another, and queries are used to search and retrieve data. A table is made up of rows and columns, and it stores data from databases.

Right-click in the Table Designer and select Relationships from the shortcut menu for the table containing the foreign key you want to examine. Select the relationship with properties you want to see in the Foreign Key Relationships dialogue box.

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Hi Team, Why you didn't teach/learn how to write select query, even you shared 15 question for practice :(

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  1. Getting Started
    18m 54s

  1. SQL Datatypes
    10m 5s
  2. SQL Commands
    21m 59s
  3. What is DBMS
    27m 51s
  4. What is RDBMS
    5m 23s

  1. Database Relationships
    11m 35s
  2. Primary Key
    6m 50s
  3. Unique Key
    3m 34s
  4. Foreign Key
    4m 2s
  5. Difference between PK, UK and PK & FK
    6m 6s

  1. SQL Server Installation Step by Step
    8m 2s

  1. How to Create Database in SQL Server
    13m 2s
  2. Assignment : SQL Create Table
    5m 5s

  1. SQL Constraints
    29m 1s
  2. SQL Insert Statement and SQL Alias
    28m 12s

  1. Filtering Data using Selection Command
    31m 53s
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    28m 52s
  3. SQL Order by Clause
    25m 56s
  4. Assignment : Ordering and Filtering
    26m 58s

  1. Aggregate Functions in SQL for Data Analysis
    22m 31s
  2. SQL Mathematical Functions for Data Analysis
    21m 31s
  3. SQL String Functions for Data Analysis
    15m 51s
  4. SQL Date & Time Functions for Data Analysis
    17m 20s
  5. SQL Window Functions for Data Analysis
    23m 34s
  6. SQL Miscellaneous Functions
    20m 10s
  7. Rollup and NTile Function
    26m 32s
  8. Row Number Function
    8m 3s
  9. DenseRank and Cumulative Distribution
    29m 12s
  10. How to use SQL Conditional Statements
    4m 22s
  11. How to use SQL Group by Clause
    4m 55s
  12. SQL Practical with Examples
    49m 46s
  13. Assignment : SQL Date and Time
    15m 16s

  1. Type of Joins in SQL - INNER, LEFT
    21m 24s
  2. Type of Joins in SQL - RIGHT,SELF,FULL, CARTESIAN
    15m 14s
  3. SQL Joins Practical Session 1
    22m 17s
  4. SQL Joins Practical Session 2
    23m 29s
  5. SQL Joins Practical Session 3
    27m 43s
  6. SQL Joins Practical Session 4
    22m 26s
  7. SQL Joins Practical Session 5
    29m 41s
  8. Assignment : SQL Joins
    15m 5s
  9. Assignment : SQL Functions 1
    13m 25s
  10. Assignment : SQL Functions 2
    9m 25s

  1. Practice: SQL Subqueries
    26m 41s
  2. Practice: SQL Subqueries & Unions
    22m 29s
  3. SQL Correlated Subqueries Part 1
    20m 21s
  4. SQL Correlated Subqueries Part 2
    30m 51s
  5. SQL Correlated Subqueries Part 3
    30m 45s
  6. SQL Correlated Subqueries Part 4
    25m 7s
  7. SQL Correlated Subqueries Part 5
    19m 42s
  8. Correlated Select, Update & Delete Queries
    33m 15s
  9. SQL Union
    18m 3s
  10. SQL EXCEPT & INTERSECT
    14m 33s
  11. Assignment : SQL SubQueries
    30m 7s

  1. SQL Pivot, UnPivot Practical Example - 1
    37m 28s
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    27m 40s

  1. What are Views?
    22m 19s
  2. Examples of SQL Views Part -1
    16m 41s
  3. Examples of SQL Views Part -2
    17m 47s
  4. Assignment : SQL Views
    10m 17s

  1. What is SQL Index?
    13m 29s
  2. SQL Index types
    24m 50s

  1. Create Tables using Select Statement
    41m 2s
  2. Using Correlated Sub Query, Group By with Select Statement
    40m 2s
  3. Using Group By and Having Clauses with Select Statement
    23m 32s
  4. Using Index Optimizer with Select Statement
    23m 24s
  5. Using Union with Select Statement
    35m 4s
  6. Adding Multiple Records with Insert Statement
    22m 42s
  7. SQL Insert - Considerations and Best Practices
    9m 19s
  8. Insertion from Multiple Tables
    22m 11s
  9. SQL Delete - Types of Delete Operation Part -1
    16m 41s
  10. SQL Delete - Types of Delete Operation Part -2
    11m 38s
  11. Assignment : SQL Insert, Update & Delete
    7m 24s

  1. Loading & Connecting Different Files in SQL
    11m 18s

  1. Course Summary
    9m 6s

  1. Interview Questions Part 1
    22m 2s
  2. Interview Questions Part 2
    20m 56s

  1. Career Guideline
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