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If the first character of a line, including indentation, is an asterisk (*) the whole line is considered as a comment, while a single double quote (") begins an in-line comment which acts until the end of the line. ABAP comments are not possible between the statements EXEC SQL and ENDEXEC because Native SQL has other usages for these characters.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Most languages support multi-line block (a.k.a. stream) and/or single line comments. A block comment is delimited with text that marks the start and end of comment text. It can span multiple lines or occupy any part of a line. Some languages allow block comments to be recursively nested inside one another, but others do not.
Since SQL is declarative, there are typically many alternative ways to execute a given query, with widely varying performance. When a query is submitted to the database, the query optimizer evaluates some of the different, correct possible plans for executing the query and returns what it considers the best option.
MATLAB was created in the 1970s by Cleve Moler, who was chairman of the computer science department at the University of New Mexico at the time. It was a free tool for academics. Jack Little, who would eventually set up the company, came across the tool while he was a graduate student in electrical engineering at Stanford University. [3] [4]
Title Authors ----- ----- SQL Examples and Guide 4 The Joy of SQL 1 An Introduction to SQL 2 Pitfalls of SQL 1 Under the precondition that isbn is the only common column name of the two tables and that a column named title only exists in the Book table, one could re-write the query above in the following form:
Delete a full conversation. Locate the thread you want to delete. Click in the box to the left of the message. Click Delete at the top of your Inbox.
Javadoc ignores comments unless they are specially marked. A Javadoc comment is marked with an extra asterisk after the start of a multi-line comment: /**. A comment block pertains to the symbol that follows the block. An example of a class header block follows: