MarkLogic Aggregation Query

MarkLogic is a Multi-model database, which combines the functions of document storage, relational database and Graph database. MarkLogic supports a variety of aggregate queries, such as aggregate functions, grouping, Inverted index, and pivot tables. The following are some common aggregation queries and their implementation examples: 1. Aggregate function: -Sum: Calculate the sum of a column Example: SELECT SUM (salary) From employees -Average: Calculate the average of a column Example: SELECT AVG (age) From employees -Maximum value: Find the maximum value of a column Example: SELECT MAX (salary) From employees -Minimum value: Find the minimum value of a column Example: SELECT MIN (age) From employees -Count: Counts the number of non null values in a column Example: SELECT COUNT (*) From employees 2. Grouping: -Group based on a column of values and calculate the aggregation results for each group Example: SELECT department, SUM (salary) From employees GROUP BY department 3. Inverted index: -Create a Inverted index on a column to efficiently query the occurrence or frequency of a value Example: SELECT word, COUNT (*) from inverted_ Index WHERE word='MarkLogic' 4. Pivot table: -Invert columns and columns, group them based on the values of a particular column, and calculate the aggregation results for each group Example: SELECT department, MAX (salary) AS max_ Salary, MIN (salary) AS min_ Salary From employees PIVOT department It should be noted that the table names (such as "employees") and column names (such as "salary" and "department") in the above examples are examples rather than specific table structures and sample data. The specific table structure and sample data may vary depending on the application scenario, and can be adjusted according to actual needs.