. . . . . . . . . . . . . . . . . . 18 10. Setting The ISC_USER And ISC_PASSWORD Environment Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 11. SQL Dialects. . . . . . . . defined. In this case, you need to supply the username and password, or create two environment variables as discussed below. The following example shows how to pass the database name plus user credentials in your options, unless users have the ISC_USER and ISC_PASSWORD declared as operating system variables. For example: isql -user SYSDBA -password masterkey Isql starts an interactive session if no options

security issues discussed this article, it merely highlights the importance of using effective environmental security in secure installations. Embedded server is discussed in more detail later. Every Firebird

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370 9. Context Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 503 MON$CONTEXT_VARIABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . database engine. Procedural SQL augments Dynamic SQL to allow compound statements containing local variables, assignments, conditions, loops and other procedural constructs. PSQL corresponds to the Part 4

Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535 11. Context Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 753 MON$CONTEXT_VARIABLES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . database engine. Procedural SQL augments Dynamic SQL to allow compound statements containing local variables, assignments, conditions, loops and other procedural constructs. PSQL corresponds to the Part 4

[ROWS [TO ]] [RETURNING [INTO <variables>]] , ::= Любые целые числа ::= value_expression [, value_expression ...] <variables> ::= :varname [, :varname ...] Ограничения ORDER BY и ROWS недоступны в ESQL; • Предложение RETURNING недоступно в ESQL; • подпункт “INTO <variables>” доступен только в PSQL; • При возврате значения в контекстную переменную NEW этому имени не [INTO <variables>]] ::= colname [, colname ...] ::= VALUES () | ::= value_expression [, value_expression ...] <variables> ::= :varname

.............................................................................. 692 MON$CONTEXT_VARIABLES .............................................................................................. 693 ROWS} ONLY]} ] [FOR UPDATE [OF ]] [WITH LOCK] [INTO <variables>] <variables> ::= [:]varname [, [:]varname ...] Описание {DEFAULT VALUES | [()] } [RETURNING [INTO <variables>]] ::= colname [, colname ...] ::= VALUES ()

database is to be displayed only. This need not be supplied if ISC_USER and ISC_PASSWORD environment variables exist and have the correct values. -password Supplies the password for the username username specified above. This need not be supplied if ISC_USER and ISC_PASSWORD environment variables exist and have the correct values. -fe[tch_password] | stdin | /dev/tty This switch descriptions of batch mode operations, assume that I have set the ISC_USER and ISC_PASSWORD environment variables. This allows gsec to be run without always having to specify the -user and -password switches.

ilegal); en vez de ello, hemos usado dos entidades A y B que son ambas NULL. A y B pueden ser campos, variables o subexpresiones enteras en su derecho – como son NULL, se comportan de la misma manera que expresiones comparar sólo valores, “is” compara estados. Colocando un campo o variable a NULL Los campos y variables pueden ser puestos a NULL usando la misma sintaxis que para valores normales: • insert into MiTabla NULL – si es necesario En muchas ocasiones, no tendrás que tomar especiales medidas para campos o variables que puedan ser NULL. Por ejemplo, si haces esto: select * from Clientes where Ciudad = 'Valencia'

nous utilisons deux entités A et B qui sont toutes deux NULL. A et B peuvent être des champs, des variables, ou des sous-expressions - du moment quelles sont NULL, elles ont le même comportement dans les » teste un état. Affecter NULL à une variable ou un champ On peut affecter NULL aux champs et variables en utilisant la même syntaxe que pour les valeurs : • insert into MyTable values (1, 'teststring' nécessaire La plupart du temps, vous n'avez pas à prendre de précaution particulière pour les champs ou variables qui peuvent être NULL. Par exemple, si vous faites ceci : select * from Clients where Ville = 'Ralston'

2. NULL support in Firebird SQL 7 if ( Buyer1 is not distinct from Buyer2 ) then... Fields, variables and other expressions are considered: • DISTINCT if they have different values or if one of them often illegal); instead, we use two entities A and B that are both NULL. A and B may be fields, variables, or even composite subexpressions — as long as they’re NULL, they’ll all behave the same in the leftmost column of the explanatory table below, “true” and “false” represent expressions (fields, variables, composites…) that evaluate to true/false. Table 2. Boolean operations on null entity A Chapter