How to compare dates in oracle

Oracle provides date comparison capabilities through operators such as = (equal), > (greater than), and < (less than). Use the DATE data type to store date values ​​and support specifying comparison dates through arguments or bind variables. Additionally, AND and OR operators are provided for multiple date comparisons, as well as special rules for handling NULL values. Other date comparison-related functions provided by Oracle include ADD_MONTHS, ADD_DAYS, and BETWEEN.

Using date comparison in Oracle

In Oracle, dates can be compared by the following methods:

1. Date comparison operators

Oracle provides several operators for comparing dates:

• =: equal
• <> or !=: not equal

• : greater than

• =: greater than or equal to

• < ;: Less than
• <=: Less than or equal to

2. Example

-- 比较两个日期是否相等
SELECT CASE
    WHEN sysdate = '2023-06-01' THEN '相等'
    ELSE '不相等'
END AS result;

-- 比较一个日期是否大于另一个日期
SELECT CASE
    WHEN sysdate > '2023-05-31' THEN '大于'
    ELSE '小于等于'
END AS result;
3. DATE data type
For date comparisons, Oracle uses the DATE data type. The DATE data type stores date values ​​without the time component. 
4. Independent variables and bind variables
In queries, you can use hardcoded dates or bind variables to specify comparison dates. 
5. Multiple date comparison
You can use AND and OR operators to compare multiple dates. 
6. NULL value
In date comparison, NULL value is treated as a special value. If one of the comparison values ​​is NULL, the comparison result is NULL. 
7. Other functions
In addition to comparison operators, Oracle also provides some functions related to date comparison, such as: 

ADD_MONTHS
ADD_DAYS
BETWEEN


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