Informative operations
They are the operations that give you information about the database schema.
- 
ColumnExist(tableName schema.TableName, columnName string) bool
 - 
ConstraintExist(tableName schema.TableName, constraintName string) bool
 - 
IndexExist(tableName schema.TableName, indexName string) bool
 - 
FindEnumUsage(name string, schemaName *string) []schema.EnumUsage
 
These functions are not reversible.