You cannot use a SELECT statement as the second argument in JOIN clauses. You can use = or = operators in the ON condition. The following query will result in error: Only JOIN (INNER JOIN) and LEFT JOIN (LEFT OUTER JOIN) are supported. For example, the following query is valid: You must use an alias for a nested SELECT statement. Consider the following example.Ĭolumns may have aliases. The following features are supported for the SELECT queries.Īccess to embedded fields by using dotted names. These wildcards are translated into a valid regular expression for MongoDB. You can use wildcards for the LIKE operator. Operands: =, =, >=,, , !=, +, -, /, *, %, AND, OR, NOT, LIKE, NOT LIKE, IS, IS NOT, IN, NOT IN, BETWEEN, NOT BETWEEN. You cannot call aggregate functions within other aggregate functions.Ĭurrently, the following functionality is supported: In SQL, there is no such dependency, and you can use aggregate functions without the GROUP BY clause (for example, SELECT AVG(x) FROM t). They are aggregate if they are placed in the group block. In MongoDB, functions like AVG, SUM, MIN, and MAX may be aggregate and non-aggregate. For example, SELECT MAX(1,2,3) will not work. Limitationsĭue to different approaches to aggregate functions in SQL and MongoDB, you cannot use aggregate functions, such as AVG, SUM, MIN, and MAX, as non-aggregate. You can see the list of all the pipeline operators that support named parameters in Aggregation Pipeline Operators at.
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