Course Intermediate  11245

Course Introduction："Self-study IT Network Linux Load Balancing Video Tutorial" mainly implements Linux load balancing by performing script operations on web, lvs and Linux under nagin.

Course Advanced  17581

Course Introduction："Shangxuetang MySQL Video Tutorial" introduces you to the process from installing to using the MySQL database, and introduces the specific operations of each link in detail.

Course Advanced  11291

Course Introduction："Brothers Band Front-end Example Display Video Tutorial" introduces examples of HTML5 and CSS3 technologies to everyone, so that everyone can become more proficient in using HTML5 and CSS3.

Course Introduction：Aggregate functions in SQL are used to calculate and return a single value for a set of rows. Common aggregation functions include: Numeric aggregation functions: COUNT(), SUM(), AVG(), MIN(), MAX() Row set aggregation functions: GROUP_CONCAT(), FIRST(), LAST() Statistical aggregation functions: STDDEV (), VARIANCE() optional aggregate functions: COUNT(DISTINCT), TOP(N)

2024-05-02 comment 0  693

Course Introduction：Aggregate functions in SQL are functions that perform calculations on a set of rows and return a single value, used to summarize and aggregate data to extract meaningful insights, including COUNT(), SUM(), AVG(), MAX(), and MIN (). They work by counting all rows, aggregating the results into a single value, and then returning the aggregated value, usually displayed in the row or column header.

2024-05-07 comment 0  1187

Course Introduction：Common SQL aggregate functions include: COUNT() to calculate the number of rows SUM() to sum AVG() to find the average MIN() to find the minimum value MAX() to find the maximum value

2024-05-07 comment 0  907

Course Introduction：Using aggregate functions in SQL often requires grouping to ensure accuracy of calculations. Grouping can be based on one or more columns, dividing the data into smaller groups and performing aggregate calculations within each group. Groupless aggregation, single-column grouping, and multi-column grouping are all viable options, depending on the aggregation function and grouping requirements.

2024-05-01 comment 0  602