PostgreSQL Functions

In this chapter we will learn about using the PostgreSQL database in the Ring programming language.

Loading the library

Before using the next function load the postgresqllib.ring library

load "postgresqllib.ring"
# Use PostgreSQL functions

Examples

Example (1):

load "postgresqllib.ring"

conninfo = "user=postgres password=sa dbname = postgres"

exit_nicely = func conn {
        PQfinish(conn)
        shutdown(1)
}

conn = PQconnectdb(conninfo)

if (PQstatus(conn) != CONNECTION_OK)
        fputs(stderr, "Connection to database failed: "+PQerrorMessage(conn))
                call exit_nicely(conn)
ok

res = PQexec(conn, "select * from pg_database")
if PQresultStatus(res) != PGRES_TUPLES_OK
        fputs(stderr, "Select failed: " + PQerrorMessage(conn))
        PQclear(res)
        exit_nicely(conn)
ok

nFields = PQnfields(res)
for i = 1 to nFields
                ? PQfname(res, i-1)
next

? copy("*",60)

for i = 1 to PQntuples(res)
        for j=1 to nFields
                see PQgetvalue(res, i-1, j-1) + " "
        next
        see nl
next

PQclear(res)

PQfinish(conn)

Output:

datname
datdba
encoding
datcollate
datctype
datistemplate
datallowconn
datconnlimit
datlastsysoid
datfrozenxid
datminmxid
dattablespace
datacl
************************************************************
postgres 10 6 English_United States.1252
        English_United States.1252 f t -1 12937 549 1 1663
template1 10 6 English_United States.1252 English_United States.1252
        t t -1 12937 549 1 1663 {=c/postgres,postgres=CTc/postgres}
template0 10 6 English_United States.1252 English_United States.1252
        t f -1 12937 549 1 1663 {=c/postgres,postgres=CTc/postgres}
mahdb 10 6 English_United States.1252 English_United States.1252
        f t -1 12937 549 1 1663

Example(2):

load "postgresqllib.ring"

conninfo = "user=postgres password=sa"

exit_nicely = func conn {
        PQfinish(conn)
        shutdown(1)
}

conn = PQconnectdb(conninfo)

if (PQstatus(conn) != CONNECTION_OK)
        fputs(stderr, "Connection to database failed: "+PQerrorMessage(conn))
                call exit_nicely(conn)
ok

res = PQexec(conn, "DROP DATABASE IF EXISTS mahdb;")
if PQresultStatus(res) != PGRES_TUPLES_OK
        fputs(stderr, "Remove failed: " + PQerrorMessage(conn))
ok
PQclear(res)


res = PQexec(conn, "CREATE DATABASE mahdb;")
if PQresultStatus(res) != PGRES_TUPLES_OK
        fputs(stderr, "Create database failed: " + PQerrorMessage(conn))
ok
PQclear(res)


res = PQexec(conn, "
CREATE TABLE COMPANY (
                 ID INT PRIMARY KEY     NOT NULL,
                 NAME           TEXT    NOT NULL,
                 AGE            INT     NOT NULL,
                 ADDRESS        CHAR(50),
                 SALARY         REAL );
")
if PQresultStatus(res) != PGRES_TUPLES_OK
        fputs(stderr, "Create Table failed: " + PQerrorMessage(conn))
ok
PQclear(res)

res = PQexec(conn, "
                INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)
                VALUES  (1, 'Mahmoud' , 31, 'Jeddah', 10.00 ),
                                (2, 'Ahmed'   , 27, 'Jeddah', 20.00 ),
                                (3, 'Mohammed', 33, 'Egypt' , 30.00 ),
                                (4, 'Ibrahim' , 24, 'Egypt ', 40.00 );
")
if PQresultStatus(res) != PGRES_TUPLES_OK
        fputs(stderr, "Insert Table failed: " + PQerrorMessage(conn))
ok
PQclear(res)

res = PQexec(conn, "
           select * from COMPANY
")
if PQresultStatus(res) != PGRES_TUPLES_OK
        fputs(stderr, "Select failed: " + PQerrorMessage(conn))
        PQclear(res)
        call exit_nicely(conn)
ok


nFields = PQnfields(res)
for i = 1 to nFields
                ? PQfname(res, i-1)
next

? copy("*",60)

for i = 1 to PQntuples(res)
        for j=1 to nFields
                see PQgetvalue(res, i-1, j-1) + " "
        next
        see nl
next

PQclear(res)

PQfinish(conn)

Output:

id
name
age
address
salary
************************************************************
1 Mahmoud  31 Jeddah  10
2 Ahmed    27 Jeddah  20
3 Mohammed 31 Egypt   30
4 Ibrahim  24 Egypt   40

RingPostgreSQL Constants

The next constants are define by the RingPostgreSQL Library

CONNECTION_STARTED
CONNECTION_MADE
CONNECTION_AWAITING_RESPONSE
CONNECTION_AUTH_OK
CONNECTION_SSL_STARTUP
CONNECTION_SETENV
CONNECTION_OK

PQPING_OK
PQPING_REJECT
PQPING_NO_RESPONSE
PQPING_NO_ATTEMPT

PGRES_EMPTY_QUERY
PGRES_COMMAND_OK
PGRES_TUPLES_OK
PGRES_COPY_OUT
PGRES_COPY_IN
PGRES_BAD_RESPONSE
PGRES_NONFATAL_ERROR
PGRES_FATAL_ERROR
PGRES_COPY_BOTH
PGRES_SINGLE_TUPLE

PG_DIAG_SEVERITY
PG_DIAG_SQLSTATE
PG_DIAG_MESSAGE_PRIMARY
PG_DIAG_MESSAGE_DETAIL
PG_DIAG_MESSAGE_HINT
PG_DIAG_STATEMENT_POSITION
PG_DIAG_INTERNAL_POSITION
PG_DIAG_INTERNAL_QUERY
PG_DIAG_CONTEXT
PG_DIAG_SCHEMA_NAME
PG_DIAG_TABLE_NAME
PG_DIAG_COLUMN_NAME
PG_DIAG_DATATYPE_NAME
PG_DIAG_CONSTRAINT_NAME
PG_DIAG_SOURCE_FILE
PG_DIAG_SOURCE_LINE
PG_DIAG_SOURCE_FUNCTION

RingPostgreSQL Functions

The next functions are define by the RingPostgreSQL Library

Reference : https://www.postgresql.org/docs/9.1/static/libpq.html

PGconn *PQconnectdbParams(const char **keywords,
        const char **values,int expand_dbname);
PGconn *PQconnectdb(const char *conninfo)
PGconn *PQsetdbLogin(const char *pghost,const char *pgport,
        const char *pgoptions,const char *pgtty,
        const char *dbName,const char *login,const char *pwd)
PGconn *PQsetdb(char *pghost,char *pgport,char *pgoptions,
        char *pgtty,char *dbName)
PGconn *PQconnectStartParams(const char **keywords,
        const char **values,int expand_dbname)
PGconn *PQconnectStart(const char *conninfo)
PostgresPollingStatusType PQconnectPoll(PGconn *conn)
PQconninfoOption *PQconndefaults(void)
PQconninfoOption *PQconninfo(PGconn *conn)
PQconninfoOption *PQconninfoParse(const char *conninfo, char **errmsg)
void PQfinish(PGconn *conn)
void PQreset(PGconn *conn)
int PQresetStart(PGconn *conn)
PostgresPollingStatusType PQresetPoll(PGconn *conn)
PGPing PQpingParams(const char **keywords,const char **values,
        int expand_dbname)
PGPing PQping(const char *conninfo)
char *PQdb(const PGconn *conn)
char *PQuser(const PGconn *conn)
char *PQpass(const PGconn *conn)
char *PQhost(const PGconn *conn)
char *PQport(const PGconn *conn)
char *PQtty(const PGconn *conn)
char *PQoptions(const PGconn *conn)
ConnStatusType PQstatus(const PGconn *conn)
PGTransactionStatusType PQtransactionStatus(const PGconn *conn)
const char *PQparameterStatus(const PGconn *conn, const char *paramName)
int PQprotocolVersion(const PGconn *conn)
int PQserverVersion(const PGconn *conn)
char *PQerrorMessage(const PGconn *conn)
int PQsocket(const PGconn *conn)
int PQbackendPID(const PGconn *conn)
int PQconnectionNeedsPassword(const PGconn *conn)
int PQconnectionUsedPassword(const PGconn *conn)
int PQsslInUse(const PGconn *conn)
const char *PQsslAttribute(const PGconn *conn, const char *attribute_name)
const char **PQsslAttributeNames(const PGconn *conn)
void *PQsslStruct(const PGconn *conn, const char *struct_name)
void *PQgetssl(const PGconn *conn)
PGresult *PQexec(PGconn *conn, const char *command);
PGresult *PQexecParams(PGconn *conn,const char *command,int nParams,
        const Oid *paramTypes,const char **paramValues,
        const int *paramLengths,const int *paramFormats,int resultFormat)
PGresult *PQprepare(PGconn *conn,const char *stmtName,
        const char *query,int nParams,const Oid *paramTypes)
PGresult *PQexecPrepared(PGconn *conn,const char *stmtName,
        int nParams,const char **paramValues,
        const int *paramLengths,const int *paramFormats,int resultFormat)
PGresult *PQdescribePrepared(PGconn *conn, const char *stmtName)
PGresult *PQdescribePortal(PGconn *conn, const char *portalName)
ExecStatusType PQresultStatus(const PGresult *res)
char *PQresStatus(ExecStatusType status)
char *PQresultErrorMessage(const PGresult *res)
char *PQresultErrorField(const PGresult *res, int fieldcode)
void PQclear(PGresult *res)
int PQntuples(const PGresult *res)
int PQnfields(const PGresult *res)
char *PQfname(const PGresult *res,int column_number)
int PQfnumber(const PGresult *res,const char *column_name)
Oid PQftable(const PGresult *res,int column_number)
int PQftablecol(const PGresult *res,int column_number)
int PQfformat(const PGresult *res,int column_number)
Oid PQftype(const PGresult *res,int column_number)
int PQfmod(const PGresult *res,int column_number)
int PQfsize(const PGresult *res,int column_number)
int PQbinaryTuples(const PGresult *res)
char *PQgetvalue(const PGresult *res,int row_number,int column_number)
int PQgetisnull(const PGresult *res,int row_number,int column_number)
int PQgetlength(const PGresult *res,int row_number,int column_number)
int PQnparams(const PGresult *res)
Oid PQparamtype(const PGresult *res, int param_number)
void PQprint(FILE *fout,const PGresult *res,const PQprintOpt *po)
char *PQcmdStatus(PGresult *res)
char *PQcmdTuples(PGresult *res)
Oid PQoidValue(const PGresult *res)
char *PQoidStatus(const PGresult *res)
char *PQescapeLiteral(PGconn *conn, const char *str, size_t length)
char *PQescapeIdentifier(PGconn *conn, const char *str, size_t length)
size_t PQescapeStringConn(PGconn *conn,char *to,
        const char *from, size_t length,int *error)
size_t PQescapeString(char *to, const char *from, size_t length)
unsigned char *PQescapeByteaConn(PGconn *conn,
        const unsigned char *from,size_t from_length,size_t *to_length)
unsigned char *PQescapeBytea(const unsigned char *from,
        size_t from_length,size_t *to_length)
unsigned char *PQunescapeBytea(const unsigned char *from, size_t *to_length)
int PQsendQuery(PGconn *conn, const char *command)
int PQsendQueryParams(PGconn *conn,const char *command,
        int nParams,const Oid *paramTypes,const char **paramValues,
        const int *paramLengths,const int *paramFormats,int resultFormat)
int PQsendPrepare(PGconn *conn,const char *stmtName,
        const char *query,int nParams,const Oid *paramTypes)
int PQsendQueryPrepared(PGconn *conn,const char *stmtName,
        int nParams,const char **paramValues,
        const int *paramLengths,const int *paramFormats,int resultFormat)
int PQsendDescribePrepared(PGconn *conn, const char *stmtName)
int PQsendDescribePortal(PGconn *conn, const char *portalName)
PGresult *PQgetResult(PGconn *conn)
int PQconsumeInput(PGconn *conn)
int PQisBusy(PGconn *conn)
int PQsetnonblocking(PGconn *conn, int arg)
int PQisnonblocking(const PGconn *conn)
int PQflush(PGconn *conn)
int PQsetSingleRowMode(PGconn *conn)
PGcancel *PQgetCancel(PGconn *conn)
void PQfreeCancel(PGcancel *cancel)
int PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
int PQrequestCancel(PGconn *conn)
PGresult *PQfn(PGconn *conn,int fnid,int *result_buf,
        int *result_len,int result_is_int,const PQArgBlock *args,int nargs)
PGnotify *PQnotifies(PGconn *conn)
int PQputCopyData(PGconn *conn,const char *buffer,int nbytes)
int PQputCopyEnd(PGconn *conn,const char *errormsg)
int PQgetCopyData(PGconn *conn,char **buffer,int async)
int PQgetline(PGconn *conn,char *buffer,int length)
int PQgetlineAsync(PGconn *conn,char *buffer,int bufsize)
int PQputline(PGconn *conn,const char *string)
int PQputnbytes(PGconn *conn,const char *buffer,int nbytes)
int PQendcopy(PGconn *conn)
int PQclientEncoding(const PGconn *conn)
char *pg_encoding_to_char(int encoding_id)
int PQsetClientEncoding(PGconn *conn, const char *encoding)
void PQtrace(PGconn *conn, FILE *stream)
void PQuntrace(PGconn *conn)
void PQfreemem(void *ptr)
void PQconninfoFree(PQconninfoOption *connOptions)
char *PQencryptPasswordConn(PGconn *conn, const char *passwd,
         const char *user, const char *algorithm)
char *PQencryptPassword(const char *passwd, const char *user)
PGresult *PQmakeEmptyPGresult(PGconn *conn, ExecStatusType status)
int PQfireResultCreateEvents(PGconn *conn, PGresult *res)
PGresult *PQcopyResult(const PGresult *src, int flags)
int PQsetResultAttrs(PGresult *res, int numAttributes, PGresAttDesc *attDescs)
int PQsetvalue(PGresult *res, int tup_num, int field_num,
                char *value, int len)
void *PQresultAlloc(PGresult *res, size_t nBytes)
int PQlibVersion(void)
PQnoticeReceiver PQsetNoticeReceiver(PGconn *conn,
                PQnoticeReceiver proc,void *arg)
PQnoticeProcessor PQsetNoticeProcessor(PGconn *conn,
                PQnoticeProcessor proc,void *arg)
void PQinitOpenSSL(int do_ssl, int do_crypto)
void PQinitSSL(int do_ssl)
int PQisthreadsafe(void)