What can be used instead of or in sql

Alternatives to the or operator in SQL include: 1. UNION: merge query results and discard duplicate records; 2. IN: check whether the value is included in the specified list; 3. CASE WHEN: return different values ​​based on conditions Value; 4. Subquery: Nested query to use the results of other queries.

Alternatives to or in SQL

In SQL queries, the or operator Used to combine two or more conditions to return records that match any one condition. However, in some cases, using or may be less efficient or difficult to read, so other alternatives may be used.

UNION

UNION operator combines the results of two or more queries, discarding duplicate records. It can be used to replace the or operator when we need to retrieve records matching specific criteria from multiple queries. The syntax is as follows:

<code class="sql">SELECT ...
FROM query1
UNION
SELECT ...
FROM query2;</code>

IN

IN The operator checks whether the value is contained in the specified list. It can be used to replace the or operator when we need to check if a value matches multiple possible values. The syntax is as follows:

<code class="sql">SELECT ...
WHERE column IN (value1, value2, ...);</code>

CASE WHEN

CASE WHEN statement allows us to perform different actions based on conditions. It can be used to replace the or operator when we need to return different values ​​based on multiple conditions. The syntax is as follows:

<code class="sql">SELECT CASE
    WHEN condition1 THEN value1
    WHEN condition2 THEN value2
    ...
    ELSE valueN
END AS column_name;</code>

Subquery

A subquery is a query nested within another query. It can be used to replace the or operator when we need to use the results of other queries in the main query. The syntax is as follows:

<code class="sql">SELECT ...
FROM main_query
WHERE condition IN (SELECT ... FROM subquery);</code>

Example

Consider the following or operator query:

<code class="sql">SELECT *
FROM table
WHERE name = 'John' OR age > 30;</code>

We can use the following alternatives:

• UNION

<code class="sql">SELECT *
FROM table
WHERE name = 'John'
UNION
SELECT *
FROM table
WHERE age > 30;</code>

• IN

<code class="sql">SELECT *
FROM table
WHERE name IN ('John', 'Mary')
OR age IN (30, 35);</code>

• CASE WHEN

<code class="sql">SELECT *
FROM table
WHERE CASE
    WHEN name = 'John' THEN TRUE
    WHEN age > 30 THEN TRUE
    ELSE FALSE
END;</code>

• Subquery

<code class="sql">SELECT *
FROM table
WHERE name = (SELECT name FROM subquery WHERE age > 30);</code>

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