I. Description
In repeated data processing, we hope that the same data will only appear once, as follows:
II. Ideas
Use SQL to remove duplicates and use designer functions to remove duplicates.
III. Solutions
1. Use ‘distinct’ in SQL
2. Use ‘group by’ in SQL
3. Use analysis functions in SQL
Some databases or databases with lower versions do not have analysis functions.
Syntax: function_name(<argument>,<argument>...) over(<partition_Clause><order by_Clause><windowing_Clause>);
function_name(): function name
argument: parameter
over( ): window function
partition_Clause: partition clause, data record set grouping, group by...
order by_Clause: sorting clause, data record set sorting, order by...
windowing_Clause: Windowing clause, which defines the set of operation rows of the analysis function, three windowing methods: rows, range, and Specifying
4. Use ‘Group’ in designer
When using this attribute, consider the influence of the parent grid.
5. Use ‘Filter Condition’ in designer
IV. Remark
Considering the impact of performance, it is recommended to use SQL to solve.