prepared-statement

问题 I have created a small 3 tier program, consisting of : front end -> servlet -> database. Front end I enter some details into a form. They are passed to a servlet, which will render some HTML and display the values entered into the form, while also calling a class DatabaseHelper. The DatabaseHelper then connects and inserts these same values into a table. I know the values are being passed to the servlet class ok, as they are being displayed in the HTML. So the problem must lie within the

问题 The following code returns 0, even though there are 5 entries in the table categories with cat = 1 . $sql = "SELECT name FROM categories WHERE cat = ?"; $stmt = $db->prepare($sql); $cat = 1; $stmt->bind_param("i", $cat); $stmt->execute(); $stmt->get_result(); echo $stmt->num_rows; However, when I change $stmt->get_result(); to $stmt->store_result(); the output is 5 . Why does get_result() not work here? I found for instance on this answer: https://stackoverflow.com/a/8722329/2311074 that get

问题 This question already has answers here : java.sql.SQLException Parameter index out of range (1 > number of parameters, which is 0) [closed] (2 answers) Closed 3 years ago . I am facing java.sql.SQLException: Parameter index out of range (3 > number of parameters, which is 2). while updating one or two columns of 'reset_info' table which has five columns (id, mobile_tower_id, reset_value, date_time, clientip). 'id' is auto-generated primary key. I want to UPDATE 'reset_value' of a particular

问题 I have the following sql prepared statement: SELECT * FROM video WHERE video_name LIKE ? Im using spring and jdbc. i have a method, where term is a searchterm, sjt is a SimpleJdbcTemplate, VideoMapper is a RowMapper and searchForTermQuery is the string from above ... return sjt.query(searchForTermQuery, new VideoMapper(), term); My table has 2 videos that match the term. However when I run the query none is found. I get an empty List. I tried playing with % around the question mark, but it

问题 Hey guys, question if this is possible or not, maybe I'm not doing something right. I'm trying to use a prepared statement where the column is prepared i.e. SELECT ? FROM users Now this normally works if I put SELECT id FROM users But doing the first statement, the value is the column name. id = id 0 = 0 What am I doing wrong, or is this possible? Thanks 回答1: No you can't bind column names or table names. Here's more info Escaping column names in PDO statements 回答2: A prepared statement can

问题 Error: Fatal error: Call to a member function bind_param() on a non-object in /var/www/web55/web/pdftest/events.php on line 76 Code: public function countDaysWithoutEvents(){ $sql = "SELECT 7 - COUNT(*) AS NumDaysWithoutEvents FROM (SELECT d.date FROM cali_events e LEFT JOIN cali_dates d ON e.event_id = d.event_id WHERE YEARWEEK(d.date) = YEARWEEK(CURRENT_DATE()) AND c.category_id = ? GROUP BY DAY(d.date) ) AS UniqueDates"; $stmt = $this->link->prepare($sql); $stmt->bind_param('i', $this-

问题 here is my very simple table (Postgres): CREATE TABLE IF NOT EXISTS PERFORMANCE.TEST ( test text NOT NULL UNIQUE ); if I try to insert a String using the command below FROM the database,everything works as expected, not surprisingly a new row appears in the DB. insert into performance.test (test) values ('abbbbaw'); However if I want to insert a String through JDBC, nothing gets inserted, although preparedStatement.executeUpdate() always returns 1. Below is my method that should be working

问题 I am trying to use a simple MySQL insert query with the parameters in array form. It keeps telling me the number of parameters are wrong. I have tried the following, all producing the same error: $stmt3 = $link->prepare('INSERT INTO messages VALUES(null, :room, :name, :message, :time, :color)'); $stmt3->execute(array(':room' => $Clean['room'],':name' => $Clean['name'],':message' => $Clean['message'],':time' => $time,':color:' => $Clean['color'])); and $stmt3 = $link->prepare('INSERT INTO

问题 I'm writing a semi-simple database wrapper class and want to have a fetching method which would operate automagically : it should prepare each different statement only the first time around and just bind and execute the query on successive calls. I guess the main question is: How does re-preparing the same MySql statement work, will PDO magically recognize the statement (so I don't have to) and cease the operation? If not , I'm planning to achieve do this by generating a unique key for each

问题 I want to insert a row into a table using PreparedStatement. The table got 3 columns(int, String, String). The thing is that the int column is AUTO_INCREMENT, so I want to leave that variable empty and let the database do that job (It's an id). Haven't found out how to do this though! It's an MySQL database. 回答1: That's relatively simple, just leave out the autoincrement column from the column list: insert into mytbl(str1, str2) values (?, ?) Prepare the statement, set the two parameters, and