what are the different types of constraints in sql?
437318
['NOT NULL - Ensures that a column cannot have a NULL value.', 'UNIQUE - Ensures that all values in a column are different.', 'PRIMARY KEY - A combination of a NOT NULL and UNIQUE. ... ', 'FOREIGN KEY - Uniquely identifies a row/record in another table.']
266848
In SQL, numbers are defined as either exact or approximate. The exact numeric data types are SMALLINT , INTEGER , BIGINT , NUMERIC(p,s) , and DECIMAL(p,s) . Exact SQL numeric data type means that the value is stored as a literal representation of the number's value.
1202551
Which of the following is not an integrity constraint? Explanation: Identical is not an allowed integrity constraint in SQL. Not null prevents null values and unique only allows unique values to be entered. ... Explanation: The not null constraint ensures that data is entered into the database.
1065603
['hierarchical database systems.', 'network database systems.', 'object-oriented database systems.']
1402370
['Values are atomic.', 'All of the values in a column have the same data type.', 'Each row is unique.', 'The sequence of columns is insignificant.', 'The sequence of rows is insignificant.', 'Each column has a unique name.', 'Integrity constraints maintain data consistency across multiple tables.']
1180091
Column-level constraints refer to a single column in the table and do not specify a column name (except check constraints). They refer to the column that they follow. Table-level constraints refer to one or more columns in the table. Table-level constraints specify the names of the columns to which they apply.
150785
['SQL Server INNER JOIN (or sometimes called simple join)', 'SQL Server LEFT OUTER JOIN (or sometimes called LEFT JOIN)', 'SQL Server RIGHT OUTER JOIN (or sometimes called RIGHT JOIN)', 'SQL Server FULL OUTER JOIN (or sometimes called FULL JOIN)']
135089
So primary key constraint means that what are the limitations which are imposed along with making any column as a primary key. The main difference is that the primary key column can only be created when you create/add the table or column, not later.
175069
['Arithmetic Operators.', 'Comparison (Relational) Operators.', 'Bitwise Operators.', 'Logical Operators.', 'Assignment Operators.', 'Special Operators.']
479629
SQL Server provides us with two main types of triggers: the DML Triggers and the DDL triggers. The DDL triggers will be fired in response to different Data Definition Language (DDL) events, such as executing CREATE, ALTER, DROP, GRANT, DENY, and REVOKE T-SQL statements.
907741
['Input: A query written in SQL is given as input to the query processor. ... ', 'Step 1: Parsing. ... ', 'Step 2: Translation. ... ', 'Step 3: Optimizer. ... ', 'Step 4: Execution Plan. ... ', 'Step 5: Evaluation. ... ', 'Output:']
1336888
['Assignment Operator.', 'Mathematical Operators.', 'Relational Operators.', 'Logical Operators.', 'Bitwise Operators.', 'Shift Operators.', 'Unary Operators.', 'Ternary Operator.']
1227701
SQL NOT NULL Constraint. By default, a column can hold NULL values. The NOT NULL constraint enforces a column to NOT accept NULL values. This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.
1414818
Unique Constraint. A constraint has different meaning to an index. It gives the optimiser more information and allows you to have foreign keys on the column, whereas a unique index doesn't.
1246361
['Arithmetic Operators.', 'Comparison Operators.', 'Logical (or Relational) Operators.', 'Assignment Operators.', 'Conditional (or ternary) Operators.']
1366385
['Inner Join. Inner join returns only those records/rows that match/exists in both the tables. ... ', 'Outer Join. We have three types of Outer Join. ... ', 'Cross Join. Cross join is a cartesian join means cartesian product of both the tables. ... ', 'Self Join.']
970074
['Numeric data types such as int, tinyint, bigint, float, real etc.', 'Date and Time data types such as Date, Time, Datetime etc.', 'Character and String data types such as char, varchar, text etc.']