Usage of (+ in oracle

The plus sign ( ) operator in Oracle can be used to: connect strings, numbers, dates and time intervals; handle NULL values ​​and convert NULL to non-NULL values; convert data types to string types.

Usage of plus sign ( ) operator in Oracle

The plus sign ( ) operator in Oracle has many Uses include:

1. Connecting strings

<code class="sql">SELECT 'Hello' || ' World';
-- 输出：HelloWorld</code>

2. Connecting numbers

<code class="sql">SELECT 12 + 34;
-- 输出：46</code>

3 . Connection date

<code class="sql">SELECT DATE '2023-01-01' + INTERVAL '1' DAY;
-- 输出：2023-01-02</code>

4. Connection time interval

<code class="sql">SELECT INTERVAL '1' HOUR + INTERVAL '30' MINUTE;
-- 输出：INTERVAL '1:30' HOUR TO MINUTE</code>

5. NULL processing

plus sign( ) operator can convert NULL values ​​to non-NULL values, as follows:

• String: NULL string = string
• Number : NULL number = number
• Date: NULL date = date
• Time interval: NULL time interval = Time interval

<code class="sql">SELECT NULL + 'Hello';
-- 输出：Hello

SELECT NULL + 12;
-- 输出：12</code>

6. Convert data type

The plus sign ( ) operator can implicitly convert the data type to a string type.

<code class="sql">SELECT '12' + 34;
-- 输出：'1234'</code>

Note:

• The plus sign () operator has higher priority than the multiplication sign (*) and division sign (/).
• For null or NULL values, the behavior of the plus () operator follows Oracle's null value handling rules.

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