SQL-用于解析+生成SQL语句的Ruby库.zip

= SQL == DESCRIPTION: Ruby library for parsing and generating SQL statements. == FEATURES/PROBLEMS: * Parse arbitrary SQL strings into an AST (abstract syntax tree), which can then be traversed. * Allows your code to understand and manipulate SQL in a deeper way than just using string manipulation. == SYNOPSIS: Here's an example of manually building an AST. It's extremely verbose at the moment, but that should be mitigated a bit when I come up with a DSL for building these trees. >> require 'rubygems' >> require 'sql' # Let's build a tree representing the SQL statement # "SELECT * FROM users WHERE id = 1" # We'll start from the rightmost side, and work our way left as we go. # First, the integer constant, "1" >> integer_constant = SQL::Statement::Integer.new(1) >> integer_constant.to_sql => "1" # Now the column reference, "id" >> column_reference = SQL::Statement::Column.new('id') >> column_reference.to_sql => "id" # Now we'll combine the two using an equals operator, to create a search # condition >> search_condition = SQL::Statement::Equals.new(column_reference, integer_constant) >> search_condition.to_sql => "id = 1" # Next we'll feed that search condition to a where clause >> where_clause = SQL::Statement::WhereClause.new(search_condition) >> where_clause.to_sql => "WHERE id = 1" # Next up is the FROM clause. First we'll build a table reference >> users = SQL::Statement::Table.new('users') >> users.to_sql => "users" # Now we'll feed that table reference to a from clause >> from_clause = SQL::Statement::FromClause.new(users) >> from_clause.to_sql => "FROM users" # Now to combine the FROM and WHERE clauses to form a table expression >> table_expression = SQL::Statement::TableExpression.new(from_clause, where_clause) >> table_expression.to_sql => "FROM users WHERE id = 1" # Now we need to represent the asterisk "*" >> all = SQL::Statement::All.new >> all.to_sql => "*" # Now we're ready to hand off these objects to a select statement >> select_statement = SQL::Statement::Select.new(all, table_expression) >> select_statement.to_sql => "SELECT * FROM users WHERE id = 1" == ROADMAP These features aren't currently implemented, but I have plans to add them in the future. Stay tuned. Eventually I plan to implement a SQL parser that will generate the tree structure for you, based on an input string of SQL. >> require 'rubygems' >> require 'sql' >> parser = SQL::Parser.new # Build the AST from a SQL statement >> ast = parser.scan_str('SELECT * FROM users WHERE id = 1') # Find which columns where selected in the FROM clause >> ast.select_list.to_sql => "*" # Output the table expression as SQL >> ast.table_expression.to_sql => "FROM users WHERE id = 1" # Drill down into the WHERE clause, to examine every piece >> ast.table_expression.where_clause.to_sql => "WHERE id = 1" >> ast.table_expression.where_clause.search_condition.to_sql => "id = 1" >> ast.table_expression.where_clause.search_condition.left.to_sql => "id" >> ast.table_expression.where_clause.search_condition.right.to_sql => "1" == REQUIREMENTS: * Ruby (duh) * RubyGems * Hoe >= 1.6.0 == INSTALL: $ sudo gem install omghax-sql --source http://gems.github.com