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update README to include errors and 'returning' values

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1 parent a777ba5 commit 240552ba416131fa23b5494971e9946bf413b048 @wg committed Jan 21, 2009
Showing with 20 additions and 8 deletions.
  1. +20 −8 README
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28 README
@@ -14,6 +14,7 @@ Erlang PostgreSQL Database Client
* Simple Query
{ok, Columns, Rows} = pgsql:squery(C, Sql).
+ {error, #error{}} = pgsql:squery(C, InvalidSql).
Columns - list of column records, see pgsql.hrl for definition.
Rows - list of tuples, one for each row.
@@ -23,17 +24,24 @@ Erlang PostgreSQL Database Client
* Extended Query
- {ok, Columns, Rows} = pgsql:equery(C, Sql, [Parameters]).
+ {ok, Columns, Rows} = pgsql:equery(C, "select ...", [Parameters]).
+ {ok, Count} = pgsql:equery(C, "update ...", [Parameters]).
+ {ok, Count, Columns, Rows} = pgsql:equery(C, "insert ... returning ...", [Parameters]).
+
+ {error, #error{}} = pgsql:equery(C, "invalid SQL", [Parameters]).
Parameters - list of values to be bound to $1, $2, $3, etc.
The extended query protocol combines parse, bind, and execute using
- the unnamed prepared statement and portal. PostgreSQL's binary format
- is used to return integers as Erlang integers, floats as floats,
- bytea/text/varchar columns as binaries, bools as true/false, etc.
+ the unnamed prepared statement and portal. A "select" statement returns
+ {ok, Columns, Rows}, "insert/update/delete" returns {ok, Count} or
+ {ok, Count, Columns, Rows} when a "returning" clause is present. When
+ an error occurs, all statements result in {error, #error{}}.
- For details see pgsql_binary.erl and the Data Representation section
- below.
+ PostgreSQL's binary format is used to return integers as Erlang
+ integers, floats as floats, bytea/text/varchar columns as binaries,
+ bools as true/false, etc. For details see pgsql_binary.erl and the
+ Data Representation section below.
* Parse/Bind/Execute
@@ -43,12 +51,14 @@ Erlang PostgreSQL Database Client
ParameterTypes - optional list of PostgreSQL types for each parameter.
For valid type names see pgsql_types.erl.
-
+
ok = pgsql:bind(C, Statement, [PortalName], ParameterValues).
PortalName- optional name for the result portal.
-
+
{ok | partial, Rows} = pgsql:execute(C, Statement, [PortalName], [MaxRows]).
+ {ok, Count} = pgsql:execute(C, Statement, [PortalName]).
+ {ok, Count, Rows} = pgsql:execute(C, Statement, [PortalName]).
PortalName - optional portal name used in bind/4.
MaxRows - maximum number of rows to return (0 for all rows).
@@ -59,6 +69,8 @@ Erlang PostgreSQL Database Client
ok = pgsql:close(C, statement | portal, Name).
ok = pgsql:sync(C).
+ All functions return {error, #error{}} when an error occurs.
+
* Data Representation
null = null

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