The SQL commands (UPDATE and DELETE) are used to modify and delete a record that is already in the database. The SQL DELETE command uses a WHERE clause and the UPDATE command also uses a WHERE condition.
The SQL UPDATE statement is used to modify existing data from a table. Here's the basic syntax for using the UPDATE statement:
SET column1 = value1, column2 = value2, ...
TableName this is the name of the table that you want to update.
column1, column2, and so on are the names of the columns you want to update.
value1, value2, and so on are the new values that you want to set for each column.
WHERE is an optional clause that lets you specify which records to update. If you skip the WHERE clause, all records in the table will be updated.
Here's an example of how you might use the UPDATE statement to change the Country of a user with a particular UserId:
SET Country= 'Canada'
WHERE UserId= 14;
This statement would update the email column of the Users table to the value Canada for the user with an UserId of 14.
Updating Multiple Fields:
If you are going to update multiple fields, you should separate each field assignment with a comma.SQL UPDATE statement for multiple fields:
SET Name= 'Arina', Country= 'Nepal'
WHERE UserId= '4'
Which SQL statement is used to update data in a database?
The UPDATE statement is the SQL statement used to update records from a database table. The UPDATE statement is used to modify the existing data in a table by changing the values of one or more columns. Here's the basic syntax for using the UPDATE statement:
SET column1 = value1, column2 = value2, ...
What does update statistics do in the SQL server
In SQL Server, the UPDATE STATISTICS command is used to update the query optimizer statistics for a specified table or indexed view. The query optimizer statistics contain important information about the distribution of data in a table or indexed view, and this information is used by the query optimizer to generate efficient execution plans for queries.
When you run the UPDATE STATISTICS command, SQL Server examines the distribution of data in the specified table or indexed view and updates the statistics accordingly. This can help improve the accuracy of the query optimizer's estimates of the number of rows that will be returned by a query and the cost of the different available execution plans.
You can run the UPDATE STATISTICS command using the following syntax:
UPDATE STATISTICS table_name [IndexName];
TableName is the name of the table or indexed view for which you want to update statistics.
IndexName is an optional parameter that specifies the name of the index for which you want to update statistics. If you omit this parameter, SQL Server will update statistics for all indexes on the table or indexed view.
For example, the following SQL statement updates the query optimizer statistics for the Employee table
UPDATE STATISTICS Employee;
This command would cause SQL Server to examine the data distribution in the Customers table and update the statistics accordingly, which could help improve the performance of queries that use this table.
UPDATE SQL from another table
In SQL, you can use the UPDATE statement to update data in one table based on data from another table. This can be useful when you need to synchronize data between two tables or when you need to update records in one table based on information in another table.
Here's an example of how to use the UPDATE statement to update records in one table based on data from another table:
SET column1 = table2.column1, column2 = table2.column2, ...
INNER JOIN table2 ON table1.key_column = table2.key_column
table1 is the name of the table that you want to update.
table2 is the name of the table that you want to use to update table1.
column1, column2, and so on are the names of the columns that you want to update in table1.
key_column is the column that is used to match records between the two tables.
condition is an optional clause that lets you specify which records to update in table1.
Here's an example that updates the price column in the products table based on the price column in the prices table, where the two tables are matched on their product_id columns:
SET price = prices.price
INNER JOIN prices ON products.product_id = prices.product_id;
This statement updates the price column in the products table to match the values in the prices table for each product_id that exists in both tables. The INNER JOIN ensures that only matching records are updated.