The Minimum grammar is a subset of the Entry Level grammar defined by SQL-92. Escape Clauses Simple standard SQL statements are reasonably portable across different SQL platforms because most vendors support at least the grammar of the 1986 SQL standard. However, more sophisticated statements like scalar functions, outer joins, or unique features such as triggers and stored procedures, are less portable. To achieve the highest degree of interoperability, use escape clauses for expressing LIKE predicates, outer joins, procedures, dates, times, timestamps and datetime intervals. You can also use escape clauses to specify scalar functions used for numeric operations, string operations and data conversions.
Escape clauses have corresponding long and short forms.
The interval escape clause provides a means of expressing time intervals and is recognized where drivers support interval data types. Example 1 . The LIKE predicate is analogous to a wildcard search argument. The underscore matches exactly one character in a column's value, and the percent sign matches zero or more characters of a search pattern. The native syntax to express an outer join isn't uniform, and not all SQL grammars include an outer join.