Posts (page 82)
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8 min readIn Rust, you can assign a value to a range of indices in a slice or array by using slicing and iteration. Here is an example of how you can achieve this: fn main() { let mut array = [1, 2, 3, 4, 5]; let values_to_assign = [10, 20, 30]; let range = 1..4; for (i, &value) in range.zip(&values_to_assign).enumerate() { array[i + range.start] = value; } println!("{:.
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4 min readIn PostgreSQL, you can write a SELECT statement inside an IF block by using the IF statement followed by the SELECT query. This allows you to perform conditional logic based on the result of the SELECT query. You can use the result of the SELECT query to determine the flow of your code within the IF block. Remember to properly handle any potential errors or unexpected results from the SELECT statement to ensure the reliability of your code.
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6 min readTo unpack a struct within another struct in Rust, you can utilize the destructuring feature that Rust provides. This allows you to access the individual fields of the inner struct by pattern matching and assigning them to variables. By deconstructing the inner struct in this way, you can easily access and work with its fields within the outer struct. This can be particularly useful when dealing with nested structs or when you need to manipulate the data stored within the inner struct.
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5 min readIn order to lock multiple table rows in PostgreSQL, you can use the SELECT ... FOR UPDATE statement. This statement allows you to lock specific rows returned by a SELECT query so that other transactions cannot modify them until the lock is released.To lock multiple rows, you can simply include a WHERE clause in your SELECT statement to specify the rows you want to lock.
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6 min readIn PostgreSQL, an alternative to the "lock_timeout" parameter is the "statement_timeout" parameter. Unlike "lock_timeout," which specifies the maximum amount of time a session will wait for a lock to be acquired, "statement_timeout" specifies the maximum amount of time a statement will run before being automatically canceled by the database server.
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5 min readWhen parsing enum arguments in Rust, you can use the clap crate to handle command-line arguments.First, define an enum that represents the possible values of your argument. Then, implement the FromStr trait for your enum so that it can be parsed from a string.Next, use the Arg::with_possible_values method in clap to specify the possible values for your argument. This will automatically generate the necessary parsing logic for your enum.
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5 min readTo select data every second with PostgreSQL, you can use the generate_series function to generate a series of numbers representing each second and then use a JOIN or WHERE clause to filter the data based on the current second. For example, you can create a query that generates a series of numbers from 0 to 59 (representing each second) and then join this series with your data to select only the rows that match the current second.
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5 min readMD5 authentication in PostgreSQL is a method used to verify the identity of database users. To use MD5 authentication, you need to configure it in the PostgreSQL server's configuration file (pg_hba.conf). In this file, you can specify which users can access the database and how they should be authenticated.To set up MD5 authentication, you need to add a line to the pg_hba.conf file that specifies the authentication method as "md5" for the users you want to authenticate using MD5.
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6 min readTo execute an implemented method in Rust, you first need to create an instance of the struct or object that contains the method. Once you have the instance, you can call the method on that instance by using the dot notation. For example, if you have a struct named MyStruct with a method named my_method, you can execute the method by first creating an instance of MyStruct and then calling my_instance.my_method().
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4 min readTo divide an annual amount into months in PostgreSQL, you can use the generate_series function to generate a series of dates covering the entire year. You can then join this series with your annual amount data and calculate the monthly amount for each month by dividing the annual amount by 12. This will give you a dataset with monthly amounts for each month of the year. This can be useful for creating financial reports or analyzing trends over time.
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5 min readTo stringify PostgreSQL JSON data, you can use the jsonb_set function to convert the JSON data into a string format. This function allows you to set a specific value in the JSON data as a string. Additionally, you can use the jsonb_typeof function to check if a specific value in the JSON data is already a string.Another way to stringify PostgreSQL JSON data is by using the jsonb_pretty function, which formats the JSON data in a human-readable string format.
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4 min readIn Rust, there is no built-in mechanism for tracking instances of structs. However, one common way to keep track of instances is to implement a counter within the struct itself. This counter can be incremented every time a new instance is created and decremented when an instance is dropped.Another approach is to use a global variable to keep track of the number of instances of a particular struct. This variable can be incremented and decremented by implementing an impl Drop trait for the struct.