prepared-statement | 易学教程

insert null for DATETIME Field through PrepareStatement using jdbc

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i want to insert null value into an DATETIME Field through PrepareStatement using JDBC (using Mysql Database) i have tried following ways but nothing is worked. i have a method " Util.dateconvertdate " it use to convert input date into a formatted string type public static String dateconvertdate(Timestamp timestamp) { Date date=null; String formattedDate=""; if(timestamp != null){ SimpleDateFormat sdf = new SimpleDateFormat("dd-MMM-yyyy hh:mm:ss"); SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss"); Date date1 = new java.util.Date(timestamp.getTime()); formattedDate =

Variable amount of columns returned in mysqli prepared statement

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I have a situation where a dynamic query is being generated that could select anywhere from 1 to over 300 different columns across multiple tables. It currently works fine just doing a query, however the issue I'm running into in using a prepared statement is that I do not know how to handle the fact that I don't know how many columns I will be asking for each time and therefor don't know how to process the results. The reason I believe a bind statement will help is because once this query is run once, it will most likely (though not always) be run again with the exact same parameters.

Best Practices with PreparedStatements; when to and when not to

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问题 I recently have began using prepared statements again in a web application, and I know that it is discouraged to use prepared statements for all the transactions. What I do not know is when it is best to use prepared statements or not. I have read of when to use and not use them, but none of the examples really tell best practice of using them. I am trying to figure out which database calls I should be using them for and which ones I should not. For Example the MySQL website mentions it in

How to Use Multiple Parameters in a MySQL Prepared Stored Procedure

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Although there are some good examples of multiple parameters being used in MySQL stored procedures, I have been unable to find a simple example that shows how to use them in a stored procedure that is prepared . The code below returns 'Incorrect arguments to EXECUTE' when calling it using: `call test_parms('my report','example.com'); I've tried with and without '@' in front of the parameter names (just gives an unknown column error), and different variations of the code . What am I doing wrong? DELIMITER $$ DROP PROCEDURE IF EXISTS `test_parms`$$ CREATE DEFINER=`root`@`localhost` PROCEDURE

PreparedStatement with CONTAINS query

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问题 I have a query that will need to run 28 000 times in a row, so I thought using a preparedStatement probably is a clever idea. Here is my query : String requestWithFirstName = "SELECT SE.ELEMENT_ID, SE.LASTNAME||' '||SE.FIRSTNAME AS ELEMENT, (SCORE(1)+SCORE(2))/2 AS SCORE " + "FROM BL_SUSPICIOUS_ELEMENT SE " + "WHERE CONTAINS(SE.LASTNAME, 'fuzzy({' || ? || '},' || ? || ',' || ? || ', weight)' , 1)>0 " + "AND CONTAINS(SE.FIRSTNAME, 'fuzzy({' || ? || '},' || ? || ',' || ? || ', weight)' , 2)>0 "

Upload PDF file to mysql BLOB by using java.sql.PreparedStatement without corruption

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问题 I tried to uplad a pdf file using java.sql.PreparedStatement to mysql Blob field using the following code. File inFile = new File("Path+BLOCK.pdf"); byte[] b = new byte[(int)inFile.length()]; PreparedStatement psmnt = (PreparedStatement) con.prepareStatement("INSERT INTO 2012DOC (SRNO,DOCUMENT) VALUES (?,?)" ); //con is java.sql.Connection object psmnt.setString(1, "1200021"); psmnt.setBytes(2, b); psmnt.executeUpdate(); This code executes without error and database shows blob content, but

mysql - Select all from one table and one column form another where $var is found

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Ooooookay. I have two tables client and users. Both have AUTO_INCREMENT id but client table has credid-column whis is foreign key and references to users table's id. I want to prepare a PHP PDO statement that fetches all columns from client-table and only username-column from users-table where client table's column credid = :var and user table's column id = :var So far I have something like this and it is not working $userid = $_SESSION['id']; //echoes a number $STH = $DBH->prepare("SELECT * FROM client WHERE credid = :id AND username FROM users WHERE id = :id"); $credentials = array( ':id' =>

MySQL append string

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问题 How can I append a string to the end of an existing table value? Let's say I have the table below: And let's say that Maria Anders not only lived in Berlin but also Tokyo. How would I append the string " Tokyo" onto the City column where ContactName = Maria Anders? P.S. I want to be able to append on to a null value as well. Thus ending up with just the one city. 回答1: Use a combination of CONCAT and IFNULL (to handle the NULL case): UPDATE `table` SET `City` = IFNULL(CONCAT(`City`, " Tokyo"),

JAVA + Mysql PreparedStatement.setString() ArrayStoreException

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I've been getting this ArrayStoreException in my code for loading records from one mysql table to another. I tried truncating the destination table and running my code again and it seems that it encounters the said exception randomly. I was going to implement a (Spring) JdbcTemplate based DAO when i've encountered an ArrayStoreException during unit testing. I tried to recreate it with ordinary JDBC code and still encounter the error. For my DDL: All the columns are of type varchar, except for brthdate and birthdate which are of type Date. DEFAULT CHARSET=utf8 My code snippet: employeesSql =

Use prepared statements everywhere in PHP? (PDO)

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问题 I'm going to be switching my database class that I use in several sites/projects, from using a custom mysql_query method*, to using PDO and prepared statements. However I have a question first - do I want to use prepared statements everywhere ? Even in places where the query will only be ran once? What about situations where I need to do something like: INSERT INTO `table` (`column`, `column`) VALUES ('value','value'), ('value','value'),('value','value'), etc. Should I use a single prepared