prepared-statement | 易学教程

C# equivalent to java prepared statement

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问题 I am trying to create a prepared statement in c#. For some reason everything I try ends up with an exeption. This is my code for now: using (OracleCommand cmd = new OracleCommand()) { cmd.Connection = conn; cmd.CommandType = CommandType.Text; cmd.CommandText = "insert into daily_cdr_logs " + "(message) " + "values " + "(:message)"; cmd.Parameters.Add(:message, msg); //OracleDbType.Int32, postpaid_duration, ParameterDirection.Input); cmd.Prepare(); cmd.ExecuteNonQuery(); } I am getting

Are there downsides to using prepared statements?

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问题 I've been reading a lot about prepared statements and in everything I've read, no one talks about the downsides of using them. Therefore, I'm wondering if there are any "there be dragons" spots that people tend to overlook? 回答1: Prepared statement is just a parsed and precompiled SQL statement which just waits for the bound variables to be provided to be executed. Any executed statement becomes prepared sooner or later (it need to be parsed, optimized, compiled and then executed). A prepared

Getting multiple rows with prepared statement

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问题 I'm quite new to prepared statements and am not sure I am doing this right. Here is what I try: $currgame = 310791; $sql = "SELECT fk_player_id, player_tiles, player_draws, player_turn, player_passes, swapped FROM ".$prefix."_gameplayer WHERE fk_game_id = ?"; $stmt = $mysqli->stmt_init(); $data = array(); if($stmt->prepare($sql)){ $stmt->bind_param('i', $currgame); $stmt->execute(); $fk_player_id = null; $player_tiles = null; $player_draws = null; $player_turn = null; $player_passes = null;

What's the life span of a PostgreSQL server-side prepared statement

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According to the PostgreSQL documentation , a prepared statement is bound to a database session/connection: PREPARE creates a prepared statement. A prepared statement is a server-side object that can be used to optimize performance. When the PREPARE statement is executed, the specified statement is parsed, analyzed, and rewritten. When an EXECUTE command is subsequently issued, the prepared statement is planned and executed. Prepared statements only last for the duration of the current database session. When the session ends, the prepared statement is forgotten, so it must be recreated before

Which should I close first, the PreparedStatement or the Connection?

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When using a PreparedStatement in JDBC, should I close the PreparedStatement first or the Connection first? I just saw a code sample in which the Connection is closed first, but it seems to me more logical to close the PreparedStatement first. Is there a standard, accepted way to do this? Does it matter? Does closing the Connection also cause the PreparedStatement to be closed, since the PreparedStatement is directly related to the Connection object? The statement. I would expect you to close (in order) the result set the statement the connection (and check for nulls along the way!) i.e. close

What does bind_param() do?

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问题 $resultSpendStmt = $connection->prepare(...); $array->bind_param("sdidi", $A, $B, $C, $D, $E); $array->execute(); $array->store_result(); $array->bind_result($F, $G, $H, $I, $J, $K); I am still a little unsure what bind_param does. Can someone give me an example as to what is means? 回答1: When you prepare an SQL statement, you can insert a placeholder ( ? ) where a column value would go, then use bind_param() to safely substitute that placeholder for the real column's value. This prevents any

Why Hibernate inlines Integer parameter list passed to JPA Criteria Query?

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问题 I am building a query using JPA Criteria API. When I created two restriction predicates using javax.persistence.criteria.Path#in(Collection<?>) method the generated SQL query was a little bit different than I excpected. The first predicate which was build over int attribute produced SQL with all elements of parameter collection inlined: in (10, 20, 30) . The second predicate which was build over String attribute produced parametrized SQL: in (?, ?, ?) . Let me show: Entity: @Entity public

bind_result into an array PHP mysqli prepared statement

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问题 wondering how i could bind the results of a PHP prepared statement into an array and then how i could go about calling them. for example this query $q = $DBH->prepare("SELECT * FROM users WHERE username = ?"); $q->bind_param("s", $user); $q->execute(); and this would return the results the username, email, and id. wondering if i could bind it in an array, and then store it in a variable so i could call it throughout the page? 回答1: PHP 5.3 introduced mysqli_stmt::get_result, which returns a

$stmt->close() vs $stmt->free_result()

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I am trying to clarify the difference between $stmt->close() and $stmt->free_result() when finalizing a prepared mysqli statement. So far I use: $mysqli = new mysqli(host,user,password,database); $stmt = $mysqli->prepare(sql statement); [...] $stmt->free_result(); $mysqli->close(); and everything seems to work fine. But I've seen a lot of programmers use $stmt->close instead of $stmt->free_result(). And once I've seen both of them: $stmt->free_result(); $stmt->close(); $mysqli->close(); So what should I choose, under which circumstances and why? $stmt->free_result() frees up memory related to

Logging PreparedStatements in Java

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One thing that always been a pain is to log SQL (JDBC) errors when you have a PreparedStatement instead of the query itself. You always end up with messages like: 2008-10-20 09:19:48,114 ERROR LoggingQueueConsumer-52 [Logger.error:168] Error executing SQL: [INSERT INTO private_rooms_bans (room_id, name, user_id, msisdn, nickname) VALUES (?, ?, ?, ?, ?) ON DUPLICATE KEY UPDATE room_id = ?, name = ?, user_id = ?, msisdn = ?, nickname = ?] Of course I could write a helper method for retrieving the values and parsing/substitute the question marks with real values (and probably will go down that