*/ Node *havingClause; /* HAVING conditional-expression */ List *windowClause; /* WINDOW window_name AS (...), ... */ /* * In a "leaf" node representing a VALUES list, the above fields are all * null, and instead this field is set. Note that the elements of the * sublists...
PL/pgSQL is a procedural language similar to Oracle's PL/SQL. It's much more powerful than pure SQL in that it supports variables, conditional expressions, looping constructs, exceptions, and the like. Because it natively supports all of PostgreSQL's SQL syntax, you can consider it a supers...
IntoClause *intoClause; /* target for SELECT INTO */ List *targetList; /* 投影列子句 */ List *fromClause; /* From子句,包括join */ Node *whereClause; /* where子句 */ List *groupClause; /* GROUP BY clauses */ Node *havingClause; /* HAVING conditional-expression */ List *windowCla...
PL/pgSQL is a procedural language similar to Oracle's PL/SQL. It's much more powerful than pure SQL in that it supports variables, conditional expressions, looping constructs, exceptions, and the like. Because it natively supports all of PostgreSQL's SQL syntax, you can consider it a supers...
List *distinctClause;/* distinct子句*/IntoClause *intoClause;/* target for SELECT INTO */List *targetList;/* 投影列子句 */List *fromClause;/* From子句,包括join */Node *whereClause;/* where子句 */List *groupClause;/* GROUP BY clauses */Node *havingClause;/* HAVING conditional-expressio...
Example 2: Using CASE WHEN in a WHERE Clause Code: -- Filter employees based on conditional logic SELECT employee_name, department FROM employees WHERE CASE WHEN department = 'Sales' THEN 1 ELSE 0 END = 1; Explanation: Only rows where the department is 'Sales' are included in the result...
What is CASE Statement and How to Write it in Postgres? As stated earlier, the CASE statement is a conditional expression, so it can be used with any statement or clause where an expression can be used, such as a WHERE clause, SELECT statement, etc. Postgres supports two forms of the ...
The where clause cannot be used to get return the desire groups. The WHERE clause can only use to restrict individual rows. When the GROUP BY has not used the HAVING works like a WHERE clause.Difference between HAVING and WHERE HAVINGWHERE HAVING clause is used for conditional retrieval of ...
*/char*filename;/* filename, or NULL for STDIN/STDOUT */List*options;/* List of DefElem nodes */Node*whereClause;/* WHERE condition (or NULL) */}CopyStmt; 权限检查 进入到DoCopy函数后,需要进行初步的权限检查。首先需要做判断的是从文件/进程导入的场景:如果是从文件导入,那么当前用户需要有读...
Conditional query constructs like the above are typically done with SELECT statements. Keep in mind that, the column must be present in the SELECT statement of your query, on which you are specifying the boolean expressions (in CASE). But when you are using CASE in pair with a where clause...