feat: Generate read-only Queries

[jarri-abidi]

Solution for #3187

no support for pgx
sorry if the code looks messy at all - open to feedback

[K-odesome]

Can we also check for delete as well if queries have

something like

DELETE FROM your_table
WHERE some_condition IN (
    SELECT some_column
    FROM another_table
    WHERE your_condition
);

[K-odesome]

Can we do it something like this

func readOnly(queries []Query) []Query {
	var rq []Query
	for _, q := range queries {
		if !q.hasRetType() {
			continue
		}

		qsql := strings.ToUpper(q.SQL)
		if !containsOnlyAllowedKeywords(qsql) {
			continue
		}

		rq = append(rq, q)
	}
	return rq
}

func containsOnlyAllowedKeywords(query string) bool {
	keywords := []string{"INSERT", "UPDATE", "DELETE","CREATE","ALTER"} // and the other keywords
		for _, keyword := range keywords {
                          if strings.Contains(qsql, keyword) {
                             return false
                          }		
	}

	return true
}

So that we can define the list of exluded words

[jarri-abidi]

queries wont/shouldn't have ddl. so we can rule out CREATE and ALTER

[jarri-abidi]

hey @kyleconroy can i get a review on this?

[jarri-abidi]

@kyleconroy is this good to go?

[jarri-abidi]

bump @kyleconroy