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9.5.1 Assignment

An assignment of a value to a PL/pgSQL variable is written as:

variable := expression;

As explained previously, the expression in such a statement is evaluated by means of an SQL SELECT command sent to the main database engine. The expression must yield a single value (possibly a row value, if the variable is a row or record variable). The target variable can be a simple variable (optionally qualified with a block name), a field of a row or record variable, or an element of an array that is a simple variable or field.

If the expression's result data type doesn't match the variable's data type, or the variable has a specific size/precision (like char(20)), the result value will be implicitly converted by the PL/pgSQL interpreter using the result type's output-function and the variable type's input-function. Note that this could potentially result in run-time errors generated by the input function, if the string form of the result value is not acceptable to the input function.

Examples:

tax := subtotal * 0.06;
my_record.user_id := 20;