```sql SELECT DATE_TRUNC('month', '2023-10-05 14:30:00'::TIMESTAMP) AS truncated_date; ``` - **INTERVAL**:用于表示两个日期或时间之间的差值,可以进行加减运算。 ```sql SELECT '2023-10-05'::DATE + INTERVAL '1 day' AS next_day; ``` 通过这些基本操作,用户可以轻松地进行日期和时间...
CREATE OR REPLACE FUNCTION DateDiff (units VARCHAR(30), start_t TIMESTAMP, end_t TIMESTAMP) RETURNS INT AS $$ DECLARE diff_interval INTERVAL; diff INT = 0; years_diff INT = 0; BEGIN IF units IN ('yy', 'yyyy', 'year', 'mm', 'm', 'month') THEN years_diff = DATE_PART('year...
The date_part('text', timestamp) function returns a double-precision number based on the requested unit, such as "hour". This function is equivalent to extract(field from timestamp), except for the quoting requirements on the unit and the presence of "from". The extract function can also ...
12, 1) end_date = datetime(2020, 12, 5) print(d
Let’s explore the COALESCE PostgreSQL function, taking a look at what it is, what it does, its pros and cons, and when to use it to handle NULL values in some real-world examples. Tools used in the tutorial Tool Description Link DBVISUALIZER TOP RATED DATABASE MANAGEMENT TOOL AND SQL ...
The PostgreSQL AGE() function subtracts two timestamps, producing a symbolic result that uses years and months. Uses of AGE() Function Calculate Age:Determine the age in years, months, and days between two dates. Date Difference:Find the difference between a specific date and the current date...
PostgreSQL的数据类型 1. 布尔类型 1.1 布尔值对应表 在Postgresql数据库中Boolean的值除了“true”(真)、“false”(假),还有一个“unknown”(未知)状态。 如果是unknown时用NULL表示。布尔类型在Postgresql中可以用不带引号的TRUE
CREATE FUNCTION add_and_subtract(a INT, b INT) RETURNS TABLE(sum INT, difference INT) AS $$ BEGIN sum := a + b; difference := a - b; RETURN NEXT; END; $$ LANGUAGE plpgsql; 然后,我们可以使用该函数来获取两个整数的和和差: 代码语言:txt 复制 SELECT * FROM add_and_subtract(5, 3...
--- 实现删除列的方法(创建新表) alter table table_name drop constraint Stockname_default --- 删除Stockname的default约束 ***function(/*常用函数*/)***---统计函数--- AVG --求平均值 COUNT --统计数目 MAX --求最大值 MIN --求最小值 SUM --求和 --AVG use pangu select avg(e_wage) as...
Here, we create a function namedCalculateAge. Furthermore, the function utilizes PostgreSQL’s built-inage()function to determine the difference between two dates. Since only one argument is provided,age()calculates the difference between the given date and the current date. Consequently, theCalcula...