Dev (#2)

* Update

Author: huanglii

docs/sql/ganos/ST_AsImage.md renamed to docs/SQL1/Ganos1/ST_AsImage.md

@@ -0,0 +1,72 @@
+---
+comments: true
+tags:
+  - GIS
+---
+
+# PostGIS
+
+## 安装
+
+```sql
+CREATE SCHEMA postgis;
+GRANT USAGE ON schema postgis to public;
+
+CREATE EXTENSION postgis SCHEMA postgis;
+CREATE EXTENSION postgis_raster SCHEMA postgis;
+
+ALTER DATABASE postgis_in_action SET search_path=public,postgis,contrib;
+```
+
+!!! info "提示"
+虽然不是必需的，但建议在单独的模式（如 postgis）中安装 postgis，这样函数就不会弄乱默认的公共模式。
+
+## 查询数据库下所有空间表
+
+```sql
+WITH columns AS (
+	SELECT
+		ns.nspname AS table_schema, -- 模式
+		cls.relname AS table_name, -- 表名
+		cls.reltuples AS tuples, -- 记录数
+		des.description AS description, -- 表描述
+		attr.attname AS column_name, -- 列名
+		col_description(attr.attrelid, attr.attnum) AS column_comment, -- 列描述
+		trim(leading '_' from tp.typname) AS column_type -- 列类型
+	FROM pg_catalog.pg_attribute attr
+		JOIN pg_catalog.pg_class AS cls ON cls.oid = attr.attrelid
+		JOIN pg_catalog.pg_namespace AS ns ON ns.oid = cls.relnamespace
+		JOIN pg_catalog.pg_type AS tp ON tp.oid = attr.atttypid
+		JOIN pg_catalog.pg_description AS des ON cls.oid = des.objoid AND des.objsubid = 0
+	WHERE
+		NOT attr.attisdropped
+		AND attr.attnum > 0
+		AND cls.relname NOT LIKE 'pg_%'
+		AND ns.nspname NOT IN ('pg_catalog', 'information_schema')
+		-- AND ns.nspname = 'other'
+		-- AND cls.relname like 'flash_flood_hazard_point'
+)
+SELECT
+	f_table_name as id,
+	f_table_schema as workspace,
+	f_table_name as data_name,
+	columns.description as description,
+	columns.tuples as tuples,
+	f_geometry_column as geometry_column,
+	type as geometry_type,
+	srid,
+	jsonb_object_agg(
+		columns.column_name,
+		json_build_object(
+			'type',columns.column_type,
+			'title',columns.column_comment
+		)
+	) AS fields
+FROM postgis.geometry_columns as gc
+	JOIN columns ON
+		gc.f_table_schema = columns.table_schema AND
+		gc.f_table_name = columns.table_name AND
+		gc.f_geometry_column != columns.column_name
+GROUP BY f_table_schema, f_table_name, description, tuples, f_geometry_column, srid, type
+
+```

docs/sql/ganos/index.md renamed to docs/SQL1/Ganos1/index.md

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+# PostgreSQL
+
+## 修改字段类型
+
+```sql
+-- 不带转换
+ALTER TABLE table_name ALTER COLUMN column_name TYPE new_type;
+
+-- 带转换
+ALTER TABLE table_name ALTER COLUMN column_name TYPE new_type USING column_name::new_type;
+```