How do I query a key-value pair in SQL?

Table of Contents

Salient points:

You can write your normal SQL queries to query for SQL in most situations.
You can do a FullTextSearch on the key-value pairs.
If your key-value pairs are simple boolean flags, this technique has the same power as having a separate column for the key.

How can I get similar names in SQL?

To find the duplicate Names in the table, we have to follow these steps: Defining the criteria: At first, you need to define the criteria for finding the duplicate Names. You might want to search in a single column or more than that. Write the query: Then simply write the query to find the duplicate Names.

How can I get last 3 characters of a name in SQL?

It could be this using the SUBSTR function in MySQL: SELECT `name` FROM `students` WHERE `marks` > 75 ORDER BY SUBSTR(`name`, -3), ID ASC; SUBSTR(name, -3) will select the last three characters in the name column of the student table.

How can you identify unique names in a dataset in SQL?

The SQL SELECT DISTINCT Statement

The SELECT DISTINCT statement is used to return only distinct (different) values. Inside a table, a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values.

How is a key-value pair database different from a relational database?

Unlike relational databases, key-value databases do not have a specified structure. Relational databases store data in tables where each column has an assigned data type. Key-value databases are a collection of key-value pairs that are stored as individual records and do not have a predefined data structure.

What is key-value format?

Key value databases, also known as key value stores, are database types where data is stored in a “key-value” format and optimized for reading and writing that data. The data is fetched by a unique key or a number of unique keys to retrieve the associated value with each key.

How do I check if two columns have the same value in SQL?

In SQL, problems require us to compare two columns for equality to achieve certain desired results. This can be achieved through the use of the =(equal to) operator between 2 columns names to be compared.

How do you find similar strings in SQL?

SQL Server: Search Similar String in a Table

Method 1 : Use LIKE operator. select data from @test. where data like ‘%test%’
Method 2 : Use CHARINDEX function. select data from @test.
Method 3 : Use PATINDEX function. select data from @test.
Method 4 : Use Regular expression. select data from @test.

How do I get last 5 characters of a string in SQL?

To get the first n characters of string with MySQL, use LEFT(). To get the last n char of string, the RIGHT() method is used in MySQL.

How do I get the first 3 characters of a string in SQL?

You can use LEN() or LENGTH()(in case of oracle sql) function to get the length of a column. SELECT LEN(column_name) FROM table_name; And you can use SUBSTRING or SUBSTR() function go get first three characters of a column.

How do I find unique values in a column in SQL?

SQL to find the number of distinct values in a column

SELECT DISTINCT column_name FROM table_name;
SELECT column_name FROM table_name GROUP BY column_name;

How do I get unique records in SQL?

SELECT DISTINCT returns only unique values (without duplicates). DISTINCT operates on a single column. DISTINCT can be used with aggregates: COUNT, AVG, MAX, etc.

What is an example of a value key pair database?

A key-value pair is the fundamental data structure of a key-value store or key-value database, but key-value pairs have existed outside of software for much longer. A telephone directory is a good example, where the key is the person or business name, and the value is the phone number.

What is a key-value pair example?

A key-value pair consists of two related data elements: A key, which is a constant that defines the data set (e.g., gender, color, price), and a value, which is a variable that belongs to the set (e.g., male/female, green, 100). Fully formed, a key-value pair could look like these: gender = male. color = green.

How do I compare values in two columns in SQL?

How do I find the difference between two values in SQL?

SQL Server DIFFERENCE() Function
The DIFFERENCE() function compares two SOUNDEX values, and returns an integer. The integer value indicates the match for the two SOUNDEX values, from 0 to 4. 0 indicates weak or no similarity between the SOUNDEX values. 4 indicates strong similarity or identically SOUNDEX values.

How do I match a pattern in SQL?

SQL pattern matching enables you to use _ to match any single character and % to match an arbitrary number of characters (including zero characters). In MySQL, SQL patterns are case-insensitive by default. Some examples are shown here. Do not use = or <> when you use SQL patterns.

What is fuzzy matching in SQL?

You can use the T-SQL algorithm to perform fuzzy matching, comparing two strings and returning a score between 1 and 0 (with 1 being an exact match). With this method, you can use fuzzy logic for address matching, which helps you account for partial matches.

How do I get last 4 digits of a string in SQL?

There is an off-by-one bug here. Should be SUBSTR(column, LENGTH(column) – 3, 4) . If the length happens to be 4, we need to start at position 1 and take 4 chars.

How do I get the first 4 characters of a string in SQL?

SQL Server LEFT() Function
The LEFT() function extracts a number of characters from a string (starting from left).

How do I extract the first 5 characters in SQL?

SQL Server SUBSTRING() Function

Extract 3 characters from a string, starting in position 1: SELECT SUBSTRING(‘SQL Tutorial’, 1, 3) AS ExtractString;
Extract 5 characters from the “CustomerName” column, starting in position 1:
Extract 100 characters from a string, starting in position 1:

How do I get the first 4 characters in SQL?

How do I check if a column contains duplicates in SQL?

How to Find Duplicate Values in SQL

Using the GROUP BY clause to group all rows by the target column(s) – i.e. the column(s) you want to check for duplicate values on.
Using the COUNT function in the HAVING clause to check if any of the groups have more than 1 entry; those would be the duplicate values.

How can I get distinct values from multiple columns in SQL?

Select with distinct on all columns of the first query. Select with distinct on multiple columns and order by clause. Count() function and select with distinct on multiple columns.

How can I get distinct values of all columns in SQL?

To get unique or distinct values of a column in MySQL Table, use the following SQL Query. SELECT DISTINCT(column_name) FROM your_table_name; You can select distinct values for one or more columns. The column names has to be separated with comma.