准备好的陈述已经存在
我正在尝试使用pg gem中的ruby中的预处理语句。 这就是我的陈述的样子
conn.prepare("insert_values", "insert into " + objectName + "(" + headerStr + ") values (" + prep_values + ")") conn.exec_prepared("insert_values", arr) 我一直在收到错误
准备好的语句insert_values已经存在。
我该如何解决？？ 谢谢
尝试运行：
conn.exec("DEALLOCATE name_of_prepared_statement")
在你的例子中：
conn.exec("DEALLOCATE insert_values")
简单的测试，它在我的irb工作：
1.8.7 :001 > require 'rubygems' => true 1.8.7 :002 > require 'pg' => true 1.8.7 :003 > conn = PGconn.connect(:host => 'localhost', :port => 5912, :user => 'test', :dbname => 'test' ) => # 1.8.7 :005 > conn.prepare("insert_values", "select * from data where id < $1") => # 1.8.7 :006 > conn.prepare("insert_values", "select * from data where id < $1 and id > $2") PGError: ERROR: prepared statement "insert_values" already exists from (irb):6:in 'prepare' from (irb):6 1.8.7 :007 > conn.prepare("insert_values", "select * from data where id < $1") PGError: ERROR: prepared statement "insert_values" already exists from (irb):7:in 'prepare' from (irb):7 1.8.7 :008 > conn.exec("DEALLOCATE insert_values") => # 1.8.7 :009 > conn.prepare("insert_values", "select * from data where id < $1") => # 1.8.7 :010 > conn.exec_prepared("insert_values",[200]) => # 1.8.7 :011 > conn.exec("DEALLOCATE insert_values") => # 1.8.7 :012 > conn.exec_prepared("insert_values",[200]) PGError: ERROR: prepared statement "insert_values" does not exist from (irb):12:in 'exec_prepared' from (irb):12
这是重用prepare()的更好方法，避免prepared statement "my_statement" already exists ：
sql = "select * from my_table where id = $1" begin ActiveRecord::Base.connection.raw_connection.prepare('my_statement', sql) rescue PG::DuplicatePstatement => e end pg_result = ActiveRecord::Base.connection.raw_connection.exec_prepared('my_statement', [my_table_id])