¿Qué hacen los dos puntos en SQL?

What Does a colon do in SQL?

The colon (:) is used to select “slices” from arrays. (See Section 5.12.) In certain SQL dialects (such as Embedded SQL), the colon is used to prefix variable names. The asterisk (*) has a special meaning when used in the SELECT command or with the COUNT aggregate function.

For built-in user-defined functions that return a table, the function name must be specified with a leading double colon (::) to distinguish it from user-defined functions that are not built-in. It also must be specified as a one-part name with no database or owner qualifications.

Psql won’t execute anything until it sees the semicolon or a “/g” and the semicolon is required to delimit multiple statements.) (“slash” commands aren’t SQL, so no semicolon. Use /? to see all the slash commands.)

That is likely referencing a bind variable. The PHP or other code that executes the MySQL statement replaces the reference with a variable. https://stackoverflow.com/questions/10393986/mysql-what-does-the-equal-colon-mean-in-an-update-statement/10394036#10394036.

Bind variables
Bind variables are the kind that must be prefixed with a colon in PL/SQL statements, such as :new discussed in the section on triggers. where the type can be only one of three things: NUMBER, CHAR, or CHAR(n). We may then assign to the variable in a following PL/SQL statement, but we must prefix it with a colon.

SQL Server comes with the following data types for storing a date or a date/time value in the database: DATE – format YYYY-MM-DD. DATETIME – format: YYYY-MM-DD HH:MI:SS. SMALLDATETIME – format: YYYY-MM-DD HH:MI:SS. TIMESTAMP – format: a unique number.

1. Arguments for SQL Functions. Arguments of a SQL function can be referenced in the function body using either names or numbers. Examples of both methods appear below. To use a name, declare the function argument as having a name, and then just write that name in the function body.

The semicolon (;) is used in SQL code as a statement terminator. For most SQL Server T-SQL statements it is not mandatory. Having said that, according to Microsoft documentation a semicolon will be required in future versions of SQL Server.

Semicolon after SQL Statements? Some database systems require a semicolon at the end of each SQL statement. Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server.

PostgreSQL supports the standard SQL to query the data or information. Queries can access multiple tables at once or can process multiple rows at the same time of the same table. Rows can be selected, updated or removed using the queries. PostgreSQL Queries with Examples

For built-in user-defined functions that return a scalar value, the function name must be specified as a one-part name (do not specify database or owner). Do not specify a leading double colon (::). Double-colons are no longer required for UDFs that return a table. However…

To do this in PL/pgSQL, use the PERFORM statement: This executes query and discards the result. Write the query the same way you would write an SQL SELECT command, but replace the initial keyword SELECT with PERFORM. For WITH queries, use PERFORM and then place the query in parentheses. (In this case, the query can only return one row.)

Using the queries that will give control of the database and allow the user to manipulate it effectively and strongly are provided in any SQL or database language. Some statements help the user have better control over the queries and help in decision-making based on PostgreSQL conditions; these statements are called the control statements.