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effects of nullthe numeric variable x perhaps of type integer might be assigned null in that case the result of evaluating x 1 is null and so set y
updating by insertionsyntaxinsert into enrolmentvalues sid s4devindercid
updating by replacementsyntaxupdate enrolment set name annwhere studentid sid s1note the use of set as already noted in connection with direct
updating variablesfor assignment sql uses the key word set as in set x x 1 read as set x equal to x1 rather than x x 1 as found in many computer
authorisations - privilegesas relational theory is silent on the issue of authorisation it offers nothing with which sqls vast edifice in support of
equivalences amp rewrite rulesif notice that as well as allowing us to prove trivial theorems and tautologies enable us to establish that certain
tautology - equivalences rulesif there tautologies are not all the time as much easy to note as the one above so than we can use these truth tables
primary keyprimary key indicates that the table is subject to a key constraint in this case declaring that no two rows in the table assigned to
sqls counterpart of the key wordsthe text from the opening parenthesis to the end of the fourth line specifies the declared type of the table meaning
creating and destroying base tablesexample shows an sql command to create the base table counterpart of the enrolment variableexample creating a
sql is a database languagethe commands given to a dbms by an application are written in the database language of the dbms the term data sublanguage
dbmsthe answer to this question is of course given in of the theory bookthis book is concerned with sql dbmss and sql databases in particular soon we
sql databaseso an sql database is one whose symbols are organized into a collection of tables now shows an sql table as the current value of an sql
task 2 12 marks write the package body for the following package specification the detailed description of each function and procedure is
write a stored procedure that accepts the post code in which the customer resides as the input parameter the procedure should then use an explicit
laws rules -dollos law laws rules -dollos law
organic evolutionevolution is a slow continuous irreversible and natural process of change to give rise to advance and diverse forms of life ie
theory of spontaneous generation - abiogenesis or autogenesis -according to this theory the existing living communities have originated from
mechanistis theory-haeckel 1866 -haeckel stating that after each catalysm some new organism suddenly forms as a chance event in one stride from
theory of catastrophism or catalysm cuvier 1769-1832 -the world has passed thorugh several stages and at the end of each stage there was a
theory of eternity of life prayer - 1880 -the theory of eternity of life also called the steady-state theory states that life has ever been in
theory of panspermia -arrhenius 1908 postulated the cosmic panspermia theory that claims that organisms existed throughout the universe and their
cosmozoic theory -richter 1865 proposed the cosmozoic theory that says that life came by spores cosmozoa or other particles from other planets on the
theory of special creation -life originated on the earth due to natural events by the super natural powerthe biblical story of creation of world
origin of earth -big-bang hypothesis -origin of life is linked to origin of earthcosmos the universe originated 10-20 billion years ago by big bang