diff --git a/doc/src/sgml/ecpg.sgml b/doc/src/sgml/ecpg.sgml index cf7681b926e..98f12979e65 100644 --- a/doc/src/sgml/ecpg.sgml +++ b/doc/src/sgml/ecpg.sgml @@ -45,15 +45,12 @@ queries. It takes care of all the tedious moving of information to and from variables in your C program. Many RDBMS packages support this embedded language. - -There is an ANSI-standard describing how the embedded language should -work. Most embedded SQL preprocessors I have seen and heard of make -extensions so it is difficult to obtain portability between them -anyway. I have not read the standard but I hope that my implementation -does not deviate too much and that it would be possible to port programs -with embedded SQL written for other RDBMS packages -to Postgres and thus -promoting the spirit of free software. + There is an ANSI-standard describing how the embedded language should +work. ecpg was designed to meet this standard as much as possible. So it is +possible to port programs with embedded SQL written for +other RDBMS packages to +Postgres and thus promoting the spirit of free +software. The Concept @@ -431,25 +428,6 @@ you are not interested in how it really works, skip this section. This version the preprocessor has some flaws: - -Preprocessor output - - -The variables should be static. - - - - - -Preprocessor cannot do syntax checking on your SQL statements - - -Whatever you write is copied more or less exactly to the Postgres and -you will not be able to locate your errors until run-time. - - - - no restriction to strings only @@ -485,51 +463,59 @@ to_date et al. records -Possibility to define records or structures in the declare section -in a way that the record can be filled from one row in the database. +Records or structures have to be defined in the declare section. + + + + +missing statements + -This is a simpler way to handle an entire row at a time. +The following statements are not implemented thus far: + + + exec sql type + + + exec sql prepare + + + exec sql allocate + + + exec sql free + + + exec sql whenever sqlwarning + + + SQLSTATE + + -array operations +message īno data foundī -Oracle has array operations that enhances speed. When implementing it in -ecpg it is done for compatibility reasons only. For them to -improve speed would require a lot more insight in the Postgres internal -mechanisms than I possess. +The error message for "no data" in an exec sql insert select from statement +has to be 100. -indicator variables +sqlwanr[6] -Oracle has indicator variables that tell if a value is null or if -it is empty. This largely simplifies array operations and provides for a -way to hack around some design flaws in the handling of VARCHAR2 -(like that an empty string isn't distinguishable from a -null value). I am not sure if this is an Oracle extension or part -of the ANSI standard. +sqlwarn[6] should be 'W' if the PRECISION or SCALE value specified in a SET +DESCRIPTOR statement will be ignored. - - -typedefs - - -As well as complex types like records and arrays, typedefs would be -a good thing to take care of. - - - - conversion of scripts