public Class Expression

checkValidCheckConstraint

collect all expressions of a set of expression types appearing anywhere in a select statement and its subselects, etc.

Overrides java.lang.Object.equals.

Doc from java.lang.Object.equals.

Indicates whether some other object is "equal to" this one.

The equals method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

An equivalence relation partitions the elements it operates on into equivalence classes; all the members of an equivalence class are equal to each other. Members of an equivalence class are substitutable for each other, at least for some purposes.

Returns the column index in the table

Returns the data type

Returns the left node

Returns the right node

For use with CHECK constraints. Under development. Currently supports a subset of expressions and is suitable for CHECK search conditions that refer only to the inserted/updated row. For full DDL reporting of VIEW select queries and CHECK search conditions, future improvements here are dependent upon improvements to SELECT query parsing, so that it is performed in a number of passes. An early pass should result in the query turned into an Expression tree that contains the information in the original SQL without any alterations, and with tables and columns all resolved. This Expression can then be preserved for future use. Table and column names that are not user-defined aliases should be kept as the HsqlName structures so that table or column renaming is reflected in the precompiled query.

Returns the type of expression

Overrides java.lang.Object.hashCode.

Doc from java.lang.Object.hashCode.

Returns a hash code value for this object. This method is supported for the benefit of hash tables such as those provided by java.util.HashMap.

The general contract of hashCode is:

• Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
• If two objects are equal according to the equals method, then calling the hashCode method on each of the two objects must produce the same integer result.
• It is not required that if two objects are unequal according to the equals method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

isCorrelated

resolve tables and collect unresolved column expressions

Set the data type